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Many of today's dirt motorcycles have electric starting, and this is a very good idea for the contemporary ultra-high compression four-stroke singles! For these operators, unless the starter fails to work, manual kicking has become a thing of the past... Despite this trend, there are still many kick-start Honda four-stroke motorcycle engines that have an "auto-decompressor" start mechanism. This device, typically mounted at one end of the overhead camshaft, unseats an exhaust valves during crankshaft rotation. The aim is to relieve compression as the piston approaches TDC (top dead center) on the compression stroke, only during kick start phase. Once the engine starts, the mechanism disengages the ramp/cam that opens the exhaust valve during kick starting. On my Honda XR650R engine, the OEM camshaft was still in place when I purchased the bike. The engine did not run, and repeated attempts to kick it over proved futile. Eventually, I ran a leak down test and discovered a considerable loss of compression caused by leaking intake valves. Despite this low compression, the kick starter repeatedly balked as if the auto-decompressor was stuck off. Even with leaking intake and exhaust valves, the engine would not kick over easily. The auto-decompressor was stuck in the off-position and acting as if not even there! Large piston displacement gave a false sense of "compression". The bike had set for some time, and perhaps this accounted for the condition of the auto-decompressor. It felt like the mechanism was sticking in the released position, providing no decompression. Even with the low compression from leaking valves, I found myself using the hand lever decompressor to "free" up the compression resistance and what felt like a jammed kick starter. Note: Wondering why an engine with leaking intake valves would still be hard to kick over? This is not hard to explain with the volume of air that this huge piston can displace, an overwhelmingly large amount compared to the amount leaking off from valve face-to-seat seepage. Given the kick start resistance, I never suspected worn, leaking valves. In fact, all four valves had a fair degree of seepage. By the time I committed to the leak down test that led to the upper engine rebuild, I had researched the XR650R engine. I'd also had enough experience (i.e., cardio workout) with the auto-decompressor to seek an aftermarket replacement camshaft without the auto-decompressor. I was not opposed to using a manual decompressor lever and knew from my first experience with a BSA 441 Victor how to find that special point, just past TDC on the compression stroke, where the engine kicks through without kicking back. Part of my rebuild was the choice to install a Hot Cams Stage 1 camshaft. This is a milder performance approach that provides more bottom end and midrange power—and a camshaft that eliminates auto-decompression. I'm good with my decision to eliminate auto-decompression and am curious how others have made peace with the factory start mechanism. Am I the only one whose auto-decompressor has stuck or jammed? I could have rebuilt and polished the OEM auto-decompressor, as the mechanism can be rebuilt. I opted out. Is everyone else happy with the stock camshaft and auto-decompressor? Please share your experiences here...An auto-decompressor is not unique to the Honda XR650R, they come in many forms and configurations, like the kick-start mechanism on my '84 XR350R, still a valve unseating approach, that has worked flawlessly and easily for three decades. From the XR600R forward, the auto-decompressor attaches to the camshaft and has a one-way clutch mechanism. How does that work for others? Moses -
The magazine recently purchased a 2000 Honda XR650R motorcycle with less than 1000 original miles on the bike. An honest and forthright previous owner could not start the engine, and given the mileage, we agreed that the problem was stale winter (ethanol) fuel—which had eaten up the plastic tank screen! I trailered the cycle home and looked forward to restoring the fuel system and completing the dual-sport conversion process. The motorcycle will be an HD video shooting platform for remote backcountry documentary filming and off-pavement event coverage, so the XR650R's low mileage seemed a huge asset. After 20 hours of prepping the cycle for a Nevada dual-sport inspection, including some minor tuning and checking out the bike's general condition, I discovered that the 650 thumper engine would not start. Consulting two friends with XR650Rs, I assumed that my starting technique was the culprit. A heavy cardio workout later, it was apparent that the compression was lacking. I did a quick compression gauge check and discovered a 95 PSI cranking compression issue. (To assure an accurate reading, make sure the auto-decompression mechanism is not holding the valves open when performing a compression test!) My next step was a cylinder leak down test, which I have covered in detail with an HD video how-to feature. (Click here to view the HD video how-to procedure and results!) The leak down test pinpointed leaking intake and exhaust valves; a look inside the cylinder (through the spark plug hole) also indicated scoring at the upper wall of the Nikasil cylinder plating. Time for an upper engine tear down, which I cover as a step-by-step HD video: Click here to see the how-to series at the 4WD Mechanix HD Video Network's freshly launched "The Off-Road Motorcycle Channel". So, how did a "bulletproof" Honda XR650R motorcycle, with less than 1000 miles since new, end up with a worn out set of valves and leaky piston and rings? The answer is two-fold: 1) the motorcycle had an incomplete "uncorking" job with a partial "Honda Power-Up Kit" installed and 2) a leaking aftermarket air filter had seeped abrasive dirt into the air stream and through the engine's intake system. The air filter issue is notorious for pitting valves, scoring an upper cylinder and damaging piston rings on motorcycle and automotive engines. An incomplete uncorking calls attention to an ever important problem for any motorcycle engine modification: the need to re-jet the carburetor to compensate for improved intake flow or a less restrictive exhaust system! The "Power-Up Kit" opened up the exhaust cap on the muffler and reduced exhaust backpressure (basically an HRC end cap). The cycle is a non-California model, so there was no restrictive "D" molding in the intake manifold grommet. (The non-California intake manifold is considered the unrestricted air intake, often sold as the upgrade for better breathing.) The pilot jet had the Power Up Kit's #68 sizing, though not the specific "68s" style. However, for some unfathomable reason, the main jet in place was still the ultra-lean, original 125 main jet! The most important ingredient in the uncorking process for a Honda XR650R motorcycle engine is the unrestricted rubber intake manifold and a jetting change to a 175 main jet and 68s pilot jet (base line at sea level). Exhaust modifications help further, the stock OE muffler's exit flow and end cap are ridiculously small for a 650 thumper! How important is the 175 main jet and 68s pilot? Important enough to be the OEM jet sizing on all Honda XR650R engines sold outside of North America! The U.S. engines were leaned to the limit by E.P.A. requirements, and California models (XR650R AC designation) were even more restricted by a draconian reshape and air flow restriction in the rubber intake manifold and the intake air box. So, this uncorked, non-California model had its exhaust opened and uncapped—plus the removal of air intake box restrictors. The EPA regulated (non-California) cycle already had the open, round intake manifold. It was in severe need of the 175 main jet, however, which the dealer neglected to install with the power tuning! The result is clear. Despite the low mileage, this engine was busy overheating its upper cylinder and valves. Upon tear down, which you can follow in the HD video linked above, the engine's upper cylinder looked more like a Baja 1000 Race finisher than 1000 miles of reasonable recreational riding. Fortunately, the previous owner had used quality lubricant and changed oil filters regularly. The XR650R's unique liquid cooling (the only XR to ever offer it!) also helped minimize damage and isolate the wear to the cylinder plating, piston skirts, rings and valves. The main engine assembly is still in near-new condition. I'm now in the process of rebuilding the upper engine. The head and cylinder have been sublet to L.A. Sleeve Company. My approach will likely be an alloy iron/chrome/moly, patented L.A. Sleeve liner in place of the factory Nikasil. Though many are fans of Nikasil, I'm not thrilled that's its only a "plating" thick. This Honda XR650R has a lot of work ahead, and it must be ultra reliable. I may consider a Stage 1 Hot Cams alternative, mainly to eliminate the auto-decompression mechanism on the OE camshaft. Compression ratio will remain the stock 10:1 with the new upgrade piston, enough squeeze for higher altitudes and the limit for kick starting and long piston ring life! Quality machine work, a fresh cylinder and upgrade piston choice, renewed valves and proper assembly technique will have this motorcycle living up to its legendary reputation—with a 175 main jet and 68* pilot jet in its Keihin carburetor! Follow the rebuild how-to coverage at the magazine's The Off-Road Motorcycle Channel—in 1080P HD video! *Note: The carburetor had a straight 68 jet installed, and I will see if the 68s is necessary. There is a difference in the flow between these two varieties. Honda's Power-Up Kit does call for the 68s and also a needle change if necessary. I will fine tune as needed, though that would be anticipated at northern Nevada. Our home base is 4,500 feet elevation and high desert; the average/mean elevation at Nevada is 5,500 feet! Moses
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I've written six 4x4 Jeep® and truck books plus a Harley-Davidson book. Most know me as a 4WD Jeep, light 4x4 truck and automotive guy, some as a Harley-Davidson author, and few are aware that motorcycling has played a role in my life. My earliest on-highway vehicle operators license, at age 14, was a Nevada Scooter License. Unique to that era, without the sanctions of insurance and high registration fees, scooters were a recognized means for getting to high school. Nevada was the fifth largest state in the U.S.—with the smallest population at the time... I rode a Cushman on the highway and a friend's Honda Trail 55 on dirt. By sixteen, my attention turned to Jeep 4WDs and muscle cars, though I never turned my back on motorcycling. My first return to two wheels was a series of three pre-owned BSA motorcycles (each '69 model year by sheer coincidence). One was a Victor 441 B44, allegedly a scrambler but rather ill-equipped for the dirt by today's standards. Cycles with vertical rear shocks and short stroke, highway style front forks were hardly off-pavement material. (This was "On Any Sunday" stuff, and many of us, including J.N. Roberts, Steve McQueen and Malcolm Smith, rode near vertical rear shock machines.) If nothing else, at nearly 10:1 compression, the Victor was the quintessential "thumper" and a good way to learn about compression release starting! Several road bikes have been notable, my BSA 650 Lightning and 750 Rocket III, a BMW R80GS (that hardly met "off-road" standards despite the implications), a BMW K1100LT that was a highway delight and a Gold Wing GL1500 that I can only call "a beast"—ridiculously cumbersome and far beyond the realm of a flick-about motorcycle. My takeaway from the Gold Wing was that I'd never ride a cycle over 500 pounds again. So much for today's "cruiser", touring bikes and dressers! As long as I can swing a leg over the saddle, I'll take a sport bike under 500 pounds, hands down. We discovered serious dirt riding and cycles two decades ago when youngest son Jacob was 11-years-old. I wanted him to ride sensibly, and a vintage XR75 was the choice after a brief detour with a Kawasaki KX80. Honda's "red" assets caught our fancy, and I acquired a used XR200R to accompany Jacob. That quickly grew to an XR350R, passing the XR200R to Jacob (typical family maneuver with motorcycles). The XR350R had been prepped and "blueprinted" by the late Rick Sorensen for his daughter Natasha to race. Rick was a topnotch aircraft A&P mechanic and motorcycle tuner...In pristine condition, this cycle has remained in my stable since, impressive enough to warrant the acquisition of an XR500R counterpart. Both are '84 model Pro-Link chassis, the 500 boasts dry-sump engine oiling...hot for the era! Yes, I do ride dirt motorcycles—with passion and vigor, desert enduro type terrain my favorite, single track or destination "overlanding" well within bounds as well. Today's cycles draw me toward an XR650R Honda for my current kind of riding, fitted with a Dakar tank and dual-sport retrofit kit, ready for long distance travel. We live at Northern Nevada, a virtual Mecca for dirt riding and backcountry motorcycling access! A CRF450X might be a consideration, though "Dust to Glory" and the XR650R are forever etched in my mind—how can Johnny Campbell, Andy Grider, Steve Hengeveld and Mouse McCoy be wrong? The XR650R Honda is the ultimate icon, a virtual cult dirt bike for the desert. So, don't be surprised if I'm regularly peeking into this forum and even adding my two-cents worth. Dirt motorcycling is on my mind—a lot. It's an incentive to stay in top physical condition, to keep my reflexes primed and not to let chronological age blur my self-concept. I'm still healthy, quick reflexed, and more than ready to ride a converted dual-sport—anywhere, any time!—Moses Ludel At left is our third XR Honda, an XR350R. We have a fourth one, too, an XR500R, for possible restoration. Or maybe we'll add an XR650R built with Baja/Dakar trim with a dual-sport conversion!...Tying to the Karavan dual-motorcycle trailer, it's time to ride in the desert. The magazine's XJ Cherokee (right) provides a good tow platform for getting the dirt bike to a trailhead or desert dry lake. A dual-sport conversion would eliminate the tow need. This cycle has done a variety of chores for more than a dozen years, included getting me around with a video camcorder for covering the Stampede Race and King of the Hammers.
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The magazine's Honda XR650R began as a potent desert enduro bike with a Baja Designs dual-sport conversion kit. The bike has power to spare, especially after the rebuild of the engine top end and installation of a Hot Cams Stage 1 camshaft. Machine work by L.A. Sleeve enhanced the performance and reliability of the motorcycle. Now street legal and plated, the platform serves our video filming in the field. This purpose built motorcycle has the inherent agility and chassis engineering to get the job done in the desert and mountainous terrain. Here, tires are a crucial consideration for a motorcycle that winds up a hundred miles from nowhere in remote backcountry. For dual-sport tires, I picked the Michelin T63 and the Michelin Cross AC10 rubber with Michelin matching tubes. If you'd like to see how I mounted and tested these tires, go to: http://www.4wdmechanix.com/4WD-Mechanix-Magazine-Tests-Michelin-Dual-Sport-Motorcycle-Tires.html. I put these tires to the test in the dirt and on highway under the brute torque of the Honda XR650R in the Part 2 video. This Honda XR650R has ample power for additional equipment. For an improved skid plate and engine side guards, plus rear bag racks, I turned to TCI Products. In the Part 2 video, you'll see this equipment and the high quality Nelson-Rigg bags that will tote gear and video equipment into the back country. Expect detailed HD video coverage on the TCI and Nelson-Rigg products shortly... Moses
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Hi Moses, I have a question about the dual-sport lighting conversion that was done on your Honda XR650R. I'm wondering what type of flasher relay was used for the turn signals. I'm trying to (re)install the turn signals on mine and, being ignorant about things electric, I am concerned that a bike with no battery may need a flasher that is different from bikes (or cars) that have batteries. The original flasher (OEM for this world-market ED/DK model) was cut out of the harness and thrown away at some point (can't figure out why though...). I went out today to find a replacement - thinking that any 12V moto flasher would do - but was only able to find 2-wire flashers, while the Honda harness provides for 3 wires. Furthermore, I was not able to find any flashers for bikes that don't have batteries. I'll look at car flashers next, but obviously none of those will have a non-battery electric system. Even if I had a source for Honda parts here, I'm not sure if the OEM flasher is available anymore - I went on the site selling international market Honda parts, and while the flasher is shown in the diagram, it is not in the price list. Are my concerns unfounded? Is a flasher just a flasher - and I only need to find one with the right amount of terminals? I know that some are designed to be impacted by the voltage draw (depending on the bulbs used), so I may end up with a fast or a slow flash, but it'd be great to at least have some kind of signal working for when I ride on the street. I can tune the flash later by changing bulbs (assuming I can find variants). Feedback welcome! David -
The 2013 SEMA and AAPEX Shows are next week (November 4-8, 2013)...I will be covering these record size events at Las Vegas, Nevada. SEMA expects over 2500 exhibits, and AAPEX has grown, too. Estimated attendance will be 140,000 at SEMA! As usual, you can expect film highlights in HD video at the 4WD Mechanix HD Video Network. By mid-November, I will also have details on the testing of Hypertech's Stage 3 Max Energy engine programming on the magazine's 2005 Dodge/Ram 3500 5.9L Cummins diesel powered pickup. We just loaded that software in time for the SEMA Show and will have 1,200 miles of real world data to share when I return from Southern California and Las Vegas, Nevada! During the week of November 1st through the 8th, I'll be scurrying around and preoccupied with a roster of key meetings with sponsors and new product tours. I'll rejoin the forums discussion on the weekend of November 9th-10th. Trust that all of the members will enjoy sharing and discussions during the week I'm covering the SEMA/AAPEX Shows! I will follow the forums through Thursday, October 31st, updating and sharing... Moses
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Speed...Yup, ethanol could be the culprit on the H-D, though two months would be short time for any damage...The needle could be stuck in its seat. Light tapping with a screwdriver handle at the float bowl will usually loosen the float needle. Quick story: My vintage Honda XR350R dirt bike set for over a year with no Stabil in the tank and "winter" (likely MTBE additive) fuel in the tank. The dual carburetors each had clogged, with the primary carb's pilot jet low enough to be submerged in the fuel bowl. The engine would not idle nor would it respond to mixture adjustments. I dropped the primary bowl with the carb in place and sprayed carburetor cleaner directly upward through the pilot jet. The jet would not clear out. I eventually removed both carburetors (not a simple task) and rebuilt them with $20 (apiece) overhaul gasket kits from Honda, rather pricey for nothing more than O-rings and neoprene gaskets. The pilot jet on the primary carburetor was so impacted with encrusted ethanol fuel that it was impossible to clean out. No amount of soaking in caustic carburetor cleaner would help, either...You cannot "drill" through plugged jets, the brass will yield and cause the hole to elongate, which increases fuel flow and modifies the fuel mixture. A new pilot jet (Keihin) and thorough carburetor rebuild and staging later, I learned not to leave "modern" ethanol or winterized fuel in the carburetor bowls. I run the engine to stall with the petcocks turned off and the bike upright. Stabil does work within reason, though fuel quickly loses its volatility when stored. In my experience, three months is the maximum age for fuel performance, and that's already a loss in performance. I like to run the bikes down low on fuel before storing, add Stabil or equivalent, then run out the fuel in the bowls. Motorcycles and ATVs/UTVs, even Jeep 4x4s, often get stored for lengthy periods. The additives in contemporary gasoline can raise havoc during long storage... Moses
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The Triumph Tiger 800 is no slouch as a showroom stock adventure-touring motorcycle. I thought the model quite cool with my ongoing affinity for British motorcycles. Last week, a visit to Freedom Cycle at Reno, Nevada, revealed what the Triumph Tiger can really do while looking like a genuine Paris-Dakar machine from the day! The dealership did the R&D on several prototype parts and modifications that make this machine not only more functional and nimble but also a magnet for attracting true adventure-touring enthusiasts. Check this out: Bucket List with "Long Way Round" and "Long Way Down" on it? This might be the machine...500 pounds fully wet! Moses
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With Nevada's now enforceable OHV registration and permitting process, many dirt motorcycle owners are at a crossroad in the Silver State. Nevada law now requires registration of a dirt bike, ATV and other OHVs for use off-highway. There is an annual renewal of the use permit, similar to a "Green Sticker" at California and other states. Owners of dirt motorcycles built since 1976 must register the motorcycle and have the option of purchasing a title. Until recent years, Nevada did not require mandatory title issuance on the sale or resale of an off-highway motorcycle. As a result, most cycles require a VIN inspection and acceptable proof of ownership or purchase. See the details at the Nevada OHV Commission's registration website page: http://nvohv.com/registration/. You will find additional links there. There is another option, no longer available in some states but currently still a prospect at Nevada: The conversion of a dirt bike for street use with a street-use title, registration, a motorcycle license plate and mandatory insurance. Until recently, dual-sport conversions were popular at adjacent California; however, the conversion of off-highway "dirt" motorcycles (deemed "off-road use" by the cycle manufacturer, DOT and EPA) has not been allowed within the Golden State since February 1, 2004. There are two exceptions: 1) motorcycles built prior to 1978, and 2) 1978-up cycles with less than 50cc displacement. Note: According to the current regulations, California dual-sport conversions were acceptable on motorcycles built through model year 2002 if the conversion was completed and paperwork submitted to the DMV prior to February 1, 2004. From January 1, 2004 forward, the DMV has required "verification" or proof that the motorcycle came with an EPA and/or California emissions label for on-highway use. This ruling about "verification" went into effect on January 1, 2004, with a one-month "grace period" during that month....If there was a street title issued within these timeframes and the cycle has current registration and street use insurance, the cycle is still legal for highway or dual-purpose use. The internet is rife with rumors, anecdotal stories and speculation about the fate of California plated dual-sport motorcycles converted after January 31, 2004. According to a statement that reflects the actual California DMV regulations, some have good reason to fear: statement of the rulings. If you're puzzled, contemplating a dual-sport conversion or considering a cycle purchase intended for California registration, read the statement and at least know where you stand. Check with the DMV about whether "grandfathering" applies when an earlier dual-sport conversion goes through a title/ownership change. Nevada is clear and sensible on the dual-sport (on- and off-highway) motorcycle conversion topic. Assuming you have a motorcycle operator's endorsement, you can ride a converted, licensed and properly insured dirt motorcycle on a public highway or any off-pavement public access roads. You will pay for a street use motorcycle title, annual registration fees and required insurance. In states allowing conversions, an acceptable dirt motorcycle must meet the legal requirements for a street motorcycle. This includes a mirror(s), a brake light activated by brake application, turn signals, a headlight (hi-low beams with a switch may be mandatory), D.O.T. approved tires, a horn, speedometer/odometer (in most states) and an acceptable exhaust tone. Some states want a license plate light of a specific brightness, and other conversion items may need to meet D.O.T. standards, like the directional signals and headlight. At Nevada and most other states, not exceeding the exhaust noise limit is just common sense, since a ticket can be issued for excessive noise. So, to ride a strictly dirt motorcycle (non-dual sport) on public land at Nevada, anywhere in the backcountry or off the paved roads, you must register and permit the cycle through the Nevada OHV Commission guidelines...There is reciprocity with other states if you're already permitted and visiting Nevada, so you may not need a Nevada permit for short-term riding at Nevada. Check the Nevada OHV Commission website for the permits honored. If you choose to convert your cycle to dual-purpose (dual-sport) use with a street use license plate, make sure you know the equipment involved. At Nevada and other states that allow conversions, you will wind up with a road-use title, annual registration renewal notification, and you must maintain proof of insurance (road use type) for both registering and riding the motorcycle. Warning: If you plan to cancel the insurance on any street legal vehicle at Nevada, make sure you surrender the license plate to the Nevada DMV first! Otherwise, expect a large fine. If you are interested in doing a dirt bike dual-sport conversion, while the opportunity still exists at Nevada and other states where reason prevails, check your state's regulations and explore the conversion kits and components available from sources like Baja Designs. Kits fit a variety of popular dirt motorcycles. Much to Nevada's credit, click here for a clear FAQ about the OHV permitting policy and the various exemptions from the OHV permit requirement—exemptions include any motorcycle licensed for use on a public highway, whether a "street" bike, factory "dual-sport" or a "dirt off-road" motorcycle converted properly (meeting State of Nevada and DOT regulations, street equipped, insured and license plated). See the FAQ for clarification—Nevada shares the details. Moses
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Snow drifts blocking your favorite dirt bike riding venues? Rainy season drenching the ground and making knee-deep mud? Does the down time in the off-season have you itching for a good ride? While you're going to the gym and anticipating the next riding season, check out this well done motorcycle enduro and trials technique instructional video depicting pro riders at South Africa! A hearty thanks to these professionals for sharing...
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Every once in a while we stumble onto some down to earth humor and genuine entertainment. All dirt bike riders who are now 50-or-older or will someday be that age will appreciate this 8-minute time out. Congratulations to these Down Under riders who know how to have a good time—and obviously have their priorities in order! Enjoy! Moses
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CTEK is the Swedish developer and manufacturer of premier battery chargers endorsed by World Class automotive and powersports brands. In an HD video how-to, learn why CTEK chargers offer superior protection against battery damage, how to properly store and protect the battery in an RV, 4x4, ATV/UTV or motorcycle, and the unique way to recondition and recover a sulphated or badly depleted battery. At the magazine, a 14:46-minute HD video is available. Here is the trailer for that video coverage with a brief overview: Enjoy the video and discover ways to protect and preserve your 4x4 and powersports batteries! Moses
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Given the opportunity to test the Pulstar® PlasmaCore spark plugs, we targeted the magazine's Honda XR350R and XR650R motorcycles. The XR350R is air cooled, the XR650R has liquid cooling. Both cycles use fixed jet, slide type carburetors. The XR350R has twin Keihin carburetors, the XR650R uses a single, large Keihin carburetor. We rode the bikes extensively. The XR350R is OHV permitted for dirt only use, and that testing took place in high desert and mountainous terrain, both dirt roads and single track. The XR650R with its dual-sport conversion received a full test at both dirt and asphalt riding. The HD video shares installation details, riding footage and an evaluation of the Pulstar® spark plugs: The magazine article is available at: http://www.4wdmechanix.com/Testing-the-Enerpulse-Pulstar-Spark-Plugs.html. We will continue testing and discussing these spark plugs at the magazine and these forums! Here are our test results and findings: Honda XR650R Motorcycle—This bike is a highway legal dual-sport conversion and ongoing project feature at the magazine. The top-engine is freshly rebuilt to "blueprint" standards, featuring a cylinder head overhaul by L.A. Sleeve Company and a moly-chrome cylinder liner with new piston and rings. We performed all work as a how-to project that became a feature HD instructional video at Vimeo On Demand. The head and upper engine work includes a Hot Cams Stage 1 camshaft. Spark timing and valve timing are "stock" with Honda Power-Up Kit tuning. This popular "uncorking" of the engine's jetting, induction system and exhaust have each been covered in detail at the magazine and the magazine's forums. This iconic motorcycle model has a large following, as the XR650R is the largest displacement enduro single cylinder bike built by Honda specifically to win the Baja 1000 and other open desert races. The magazine's viewers and forum members have followed the performance gains made with this engine build-up and tuning. The addition of the Enerpulse Pulstar® spark plug provided these noticeable results: 1) Since the rebuild and tuning, the engine has produced superior torque (49 lb-ft estimated) and a high horsepower output (approximately 55 horsepower). Along with the Pulstar® spark plug change, we added a 6.3 gallon fuel tank (5 extra gallons of fuel at approximated 40 pounds net weight gain between the fuel and the large tank) to the motorcycle. Testing the Pulstar® spark plug, performance with the additional weight is slightly better than with the lighter 2.6 gallon factory fuel tank. 40 extra pounds is significant for a dirt enduro motorcycle. When we reinstalled the 2.6 gallon tank for further testing, acceleration and throttle response showed noticeable improvement. Torque increased, and fewer downshifts were necessary under load. 2) A converted dual-sport, highway legal machine, the XR650R is kick start only. Tuning has enabled ready starts with a stock-type NGK spark plug. The Pulstar® spark plug fires the engine with equal ease. 3) Flooding is always a concern on a large displacement single cylinder motorcycle engine. The Pulstar® spark plug strongly resists fuel fouling. The spark plug readily fires through richer mixtures at altitude. 4) This engine has a fixed-jet factory Keihin slide-type carburetor. Altitude sensitivity is always an issue with fixed jets. Larger displacement engines are more susceptible to fuel fouling at higher altitudes. The Pulstar® spark plug, with superior spark output and more complete fuel burn, clearly maximizes performance over a wider range of altitude—even with a fixed jet carburetor. During the road and dirt testing, this motorcycle operated between 4,400 and 7,600 feet elevation with no sign of "rich" mixture spark plug fouling. The fixed carburetor jet setting is for 1,500 and 5,000 feet elevation. Clearly, the Pulstar® spark plugs burn cleaner and more efficiently, producing better power and performance at higher altitudes. Honda XR350R Motorcycle—This OHV bike is strictly set up for dirt riding. The stock motorcycle was upgraded for desert hare-and-hound scrambles, tuned and jetted for optimal performance at 4,400 feet altitude with the stock factory dual Keihin carburetors. In top condition, with normal compression and peak tuning, the only change was the switch to a Pulstar® spark plug. Our extensive testing in the high desert and mountains spans from 4,000 feet elevation to 6,500 feet elevation. A single cylinder, air cooled engine provides an optimal test bed for combustion and fuel burn comparisons. Pulstar® spark plug test conclusions: 1) Starting is easy whether cold or hot. Starts readily with the choke on. Warms normally as with the stock type NGK spark plug. 2) Throttle response is crisp and noticeably improved. Engine stability under load has improved, requiring less downshifting to compensate for load. (Watch the video.) 3) Again, the most significant gain is less sensitivity to altitude changes with fixed jets in these two carburetors. We operated the motorcycle from 4,000-6,500 feet without adjusting the carburetors or altering the jets. The motorcycle performed flawlessly. 4) This motorcycle has always been miserly on fuel compared to two-stroke engines or larger displacement four-stroke thumpers. Testing revealed a noticeable improvement in fuel efficiency. The motorcycle ran our pre-determined course under load and used less fuel-per-hour than with the stock-type NGK spark plug. This improvement can only be attributed to the Enerpulse Pulstar® spark plug. We'll continue to evaluate these spark plugs over time. They offer a significant breakthrough in spark and combustion technology. Enjoy the video! Moses
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When I pondered buying a Honda XR650R motorcycle, my BRP research spanned the web. Repeatedly, I unearthed references and horror stories about how tough it is to start these engines. Forums were rife with starting and kicking rituals, choking methods and decompression lever habits. Add the mention of stock and aftermarket carburetors, suggestions on how to use the manual decompressor, descriptions of how best to use auto-decompression, you name it. Eventually, one could get leery of approaching one of these critters or maybe buy a newer electric start KTM EXC. Common sense prevailed, after all, this is just a four-stroke motorcycle engine with 10:1 compression. I bought a BRP anyway. So affected was I that when I completed a top-engine build that should start, I didn't expect the engine to start! (Objectively, some of this carried over from the several days of trying to start the BRP with a 90% cylinder leakage prior to the restoration of the top end.) The compression was spot on, valve and spark timing perfect, a new spark plug gapped properly, and preliminary carburetor settings "by the book". The carburetor jetting, exhaust flow and choke were correct. I had even check over the carburetor, though I would subsequently "blueprint" rebuild it. With a stock Keihin carburetor jetted to known norms that make sense for this engine and our region's altitude, everything pointed to an engine that would start... I decided to use the same technique that always started my dual-carbureted '84 XR350R and '84 XR500R in sub-freezing weather or scorching summer heat. These are each motorcycles that many will never own because the "dual carburetors are junk!" This is good for the rest of us, as these four-valve thumpers are wonderful machines when tuned with the carbs sync'd properly! We can pick a nice bike up cheap. Just one example was an "as new", stored '84 XR500R that recently sold at a renown motorcycle auction for $2800. Wish I'd been there. These auctions usually generate a "fever" that drives prices to ridiculous heights, but not for a four-valve Honda thumper that has dual carburetors. Thanks to the internet, the word is out! After all the hype around BRPs and hard starting, I settled for a more rational approach—knowing that this engine should most certainly start well! And you know what? It did. Cold, I can start this engine on the first or second kick when applying the choke correctly. Once warm, as in this video, one kick ought to do it! Yet ahead, there's still the internet scuttlebutt and portent of "how bad these engines restart after laying them on their side". I've consciously avoided doing this so have no comment yet. I do have an approach for that, should the unplanned occasion present itself, and I bet it will work! This video is an honest to goodness, candid start-up of the engine. My GoPro Chesty was on for the morning's second round of Acerbis tank road testing. The bike had been setting in the driveway for twenty minutes, minding its own business. I used the manual decompressor lever simply to tickle the piston past TDC on the compression stroke...Judge for yourself. This is a properly tuned Honda XR650R. I'll make a point of filming a start-up with the dual-carbureted XR350R next time I ride it. Let's cross fingers that won't drive the price up on vintage dual-carbureted XRs!—Moses
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In the 1990s, we began riding Honda XR dirt motorcycles. In the early '90s a modest $75 worth of parts invested in a Honda XR75 became youngest son Jacob's first motorcycle at age 12. Oregon friend Kirk donated two core bikes to the cause from his stockpile of old Hondas. When we returned to the high desert country at northern Nevada in 1994, my logical companion for Jacob's XR75 was a used 1983 Honda XR200R purchased from the Reno dealership. Jacob soon outgrew the XR75, and I outgrew the XR200R thumper. Jacob inherited the XR200R when I found the right four-stroke bike, a very well prepped 1984 Honda XR350R built by Rick Sorensen, a professional Airframe and Powerplant aircraft mechanic and owner of an independent motorcycle shop at Yerington, our hometown. Rick built the machine for his daughter Tasha to potentially race hare-and-hound, and she prized the machine. Tasha went to college, and while a student, she offered the bike for sale. Knowing how much energy and upgrade equipment Rick had put into this purpose built machine, I gladly paid Tasha her asking price. The bike received my respect as well, and it continued to deliver everything from bona fide desert enduro riding at speed to tight, single track trailing on the steep, off-camber switchbacks leading to mining claims at Black Mountain. The XR350R was a great teacher, its Pro-Link rear suspension, advanced forks for the era, rugged tubular steel frame and bulletproof four-valve, single cylinder engine were predictable and ample. In the day, a six-speed gearbox and advertised weight under 250 pounds had made the XR350R popular alongside its potent yet beefier XR500R counterpart. Rated 22.4 horsepower by most accounts, the 1984 engine featured some upgrades yet still maintained the progressive dual carburetors for the twin intake port, four-valve head. From a tuning standpoint, the dual carburetors were condemned by many, as this was the period when single cylinder engines commonly had only one carburetor. Although the rumor mill is rife with attacks on these twin-Keihin carburetors, I have never experienced trouble with this design. In fact, the tune that Rick Sorensen set was so precise that the only cause for rebuilding these carburetors came a decade after acquiring the machine. My rebuild had nothing to do with a deficiency in the carburetors but rather the result of leaving ethanol-laced gasoline in the bowls too long and ruining the pilot jet on the primary carburetor. I "blueprint" built and staged these carburetors, and the performance went right back to Rick's original aims. I've had several opportunities to part with this machine, offers from those who know its virtues and steadfast ability to pull off a great day's riding, anywhere and anytime, from High Rock Canyon to Johnson Valley when I covered the King of the Hammers race in 2012. Appreciation for its consistent performance and exceptional reliability has kept me from letting go of this machine, which is now relegated to occasional recreational riding since the acquisition and build of the "Big Red Pig" Honda XR650R. Our youngest grandson, Camden, now 2-1/2 years old, calls the XR350R "Little Red Pig" and the XR650R the "Big Red Pig". My '84 XR500R restoration project, while under a dry tarp at present, is nonetheless the "Middle Red Pig"—or simply "Middle". Honda XR350R Specs.pdf It's pointless to compare the air-cooled Honda XR350R to the XR650R, the latest CRF450X or KTM 350. The vintage XR350R four-valve thumper has nowhere near the power hit of an XR500R, XR600R or the liquid cooled XR650R. However, for many riders, the XR350R can be the weekend desert enduro bike with a low initial purchase price and far less maintenance cost if in good condition with a credible history. These bikes perform trouble free for years, and they wear out slowly and predictably. Parts are still available for most areas of the cycle. Used pieces or improvising are sometimes necessary. I ride my XR350R to stay in good physical condition and to maintain agility and survival reflexes for both dirt and asphalt motorcycling. Easier to throw around on dirt than heavier machines, the bike provides excellent terrain feedback and continuously works all five of my muscle groups! My most recent workout on the XR350R was a test of the Enerpulse Pulstar PlasmaCore spark plug this morning. I filmed my ride with the GoPro Hero3 mounted in a Chesty harness. The edited video default is HD 1080P, and if you have the bandwidth or can stream Vimeo on the big screen through your Roku, Apple TV, Chromecast or Amazon Fire TV player*, enjoy the scenery! (Otherwise, there's the subtler SD play option.) *Note: If you have one of these streaming players, simply do a search under "4WD Mechanix". You'll have access to the 190 videos now available at the Vimeo 4WD Mechanix Video Network Channel! If you have a smart television or large computer monitor, simply go to the Vimeo Channel at: http://www.vimeo.com/channels/4WDmechanix. The riding venue begins just ten minutes from the 4WD Mechanix Magazine office...Take a 15-minute ride with me as the XR350R ascends from a high desert elevation of 4,000 feet into the nearby mountains and wild horse country over 6000 feet. This is what desert enduro motorcycling is all about! See why this three decade old "friend" has remained my recreational dirt bike and exercise outlet for nearly twenty years now... Moses
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Hi, Moses! I fell across this website recently while researching some pieces of aftermarket hardware that are on the 2002 plated BRP I purchased here in Bend, OR recently. Saw the bike on Craigslist and thought it looked like fun on the road! I also have a 2001 BRP that I purchased in 2002 which has been lovingly flogged for 12 years now. Reading your blog and many others, It appears the XR650R is a cult classic...Guess I was not aware how good of a bike I had! I too am a graduate from the Univ. of Oregon, 1985. In 1983 I bought a new XR500R for commuting Eugene to home in Florence on the weekends. I had this brilliant idea to take a dirt bike and convert it to some highway fun. Found a motorcycle wrecking yard in Springfield and put all the necessary used parts on the bike to make it street legal and get it through DMV for a license plate. Ran everything off the magneto and used my rear brake as a way to dim the head light for oncoming cars at night. Crude but it worked! I was the terror of campus and nothing was off limits...The girls loved it! 3rd floor dorm (Tingle) I used for parking when it was time for maintenance. Had fun for almost 2 years until "the terror of campus" was stolen. Since then I have had numerous bikes (including a new '87 XR600R owned until the 2001 XR650R), but always wanted more fun with a road worthy XR. So when I saw this converted 2002 BRP, I knew I had to have it. And what fun to re-live old college memories and make new ones. This bike HAULS BUTT on the road and satisfies this mid-life crises. Absolutely the most fun OTR (on the road!) I have ever had. Thanks for the XR650R review for racks, rebuild, and tires. I will be following your BRP experiences. BTW, cold start procedures are a one-kick affair, and if I lift my rear off the seat to do this than I'm trying too hard! S. Ellson -
Well, I rode the Honda XR650R motorcycle this morning, not unusual in itself, as I've been trying to rack up miles on the top-end engine rebuild in time for Fall riding. One thing was unusual, though. At 204 miles since the rebuild that included L.A. Sleeve machine work, the bike has reached a whole new performance level! The magazine's Honda XR650R top-engine teardown and inspection. My morning riding venue is typically rural highways, both two-way traffic two lanes and divided highway four-lane. I've been on dirt with the Michelin T63 tire tests and have much more planned, this Fall will be extensive dual-sport riding both on- and off-highway. Customarily, these cooler morning rides have been intended to run the engine up and down the light load and rpm scale, nothing stressful, just steady rpm stretches mixed with changes in speed and load. The beginning to present: Our XR650R evolves from a desert bike with a dual-sport conversion into a bona fide video filming platform and road/trail adventure profile bike! Take a ride with us. Still in the break-in phase, this cycle is already "badass"! I've continually added weight to the bike, though this was not my original plan. Sleek and race-bred, these bikes look quite "cool" stripped to competition desert enduro form. In our case, though, the dual-sport conversion and additional TCI Products racks with Nelson-Rigg bags have been a necessity for carrying our video filming equipment. The motorcycle is highly versatile and can also serve as a "support" bike for backcountry group riding at remote areas like Moab or the Black Rock/High Rock Canyon. All of that said, I should probably weigh the bike "wet" with the racks and bags (at least empty) to answer a fundamental question: Why is this bike evolving into the most badass of any dirt bike I've ever owned and ridden? Despite the add-on items, and my current dry weight of 178-180 pounds, the Honda XR650R just keeps getting stronger! This motorcycle clearly has the best roll-on throttle, from idle to higher rpm, of any desert enduro cycle in its class. This performance applies in any gear, at any throttle position opening and regardless of roll-on road speed! No wonder these motorcycles dominated the long Baja races until Honda pulled them... Note: Sprocket gearing is 14/48 (stock N.A. enduro form) with the tires described in the Michelin T63 tests. Some XR650R models, like Australia export, have taller gearing. This bike tops out at over 100 mph, and that's plenty, thanks! Worth noting, with this gearing, that speed comes up remarkably fast. Collaboration with L.A. Sleeve reaped big results. The cylinder head rework, iron/moly/chromium cylinder liner plus quality replacement parts help account for the bike's impressive performance! A Hot Cams Stage 1 camshaft adds to the impressive torque output. Part of this is tune, which includes the official N.A. Power Up Kit ("uncorking") and use of a Hot Cams Stage 1 camshaft with L.A. Sleeve head and cylinder work. I'm looking forward to comments from Greg and David about the performance of their Honda XR650R machines, as the acceleration and on-tap torque—idle speed up—of the magazine's machine is quite impressive. The camshaft obviously plays a role, and we need to compare this machine with two XR650R models that are "uncorked" and without the camshaft upgrade. Frankly, this Stage 1 camshaft that eliminates the auto-decompression mechanism on the camshaft has no downside. I can start this engine cold or hot in one or two kicks, using the handlebar decompression lever for manual tick-over. So, I'm waiting for others to jump into this discussion. How does the Honda XR650R compare to the best contemporary 450cc and 500cc class four-stroke enduro bikes? Is the XR650R new enough technology to excel over a field of later bikes with less displacement yet higher compression and EFI? Would anyone with another make and model desert enduro bike care to comment? I'd like to objectify my experience, as frankly, this bike really does act badass! Moses
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The magazine's Honda XR650R performs remote field work as an HD video filming platform. Reliability is essential. After purchasing the bike in non-running condition, I ran a compression test when the engine refused to start. I moved from the simple compression test to a full-fledged cylinder leak down test, the pinpoint diagnostic tool of choice. Want to know more about a leak down test? Click here for the 4WD Mechanix HD Video Network feature and details on the leak down test! High cylinder leakage called for a top end inspection and repairs. That tear down for inspection can be found at the magazine as the HD video how-to: http://www.4wdmechanix.com/Honda-XR650R-Motorcycle-Upper-Engine-Rebuild-Part-1-Tear-Down-How-to.html. At left is the cylinder leak down test covered in the HD video how-to. At right is the actual top engine tear down, part of the current rebuild. See both HD videos at the magazine for details! The step-by-step teardown, rebuild and assembly are now a single HD video streaming rental at Vimeo On Demand. Included in this rental is a bonus feature on valve adjustment (which is also available as a separate streaming rental). You will find this 54-minute feature at: http://www.vimeo.com/ondemand/hondaxr650r. Here is a review of that rental video: "Coming across this video couldn't have been more fortuitous - both in timing and content. I happened to inherit a motorcycle of the exact same type and with the exact same problems as the one starring in the clip. The author/producer treats the subject thoroughly and with close-ups giving great detail of the matter at hand. Not only that, he has an online magazine with a forum through which he is eminently available for input and feedback. Having watched this gave me the confidence to embark on the solution on my own - saving loads of money and learning in the process."—David E.
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It all began with a passion for desert enduro bikes. After a dozen viewings of "Dust to Glory!", my bike of choice was the Honda XR650R liquid cooled thumper. Finding the right used machine, rebuilding the engine top-end with machine work by L.A. Sleeve, dialing the tune, after months of waiting, I finally mounted the beast and headed into the desert. An hour of dirt riding validated my choice, for my kind of riding, this is the perfect motorcycle. Fresh top-end rebuild with a Hot Cams Stage 1 camshaft, the magazine's XR650R is ready for the desert! With an estimated 55 horsepower and 50 lb-ft torque in this form, the bike will meet every performance demand. My original goal with this motorcycle was a reliable, highly capable motorcycle for HD video filming at off-road events and travel-adventure rides. And now I faced a significant obstacle: Where would I put all the camping and video gear? Was a purpose built enduro motorcycle able to perform double duty like this? Michelin T63 and Cross AC10 tires were the first step toward taming the desert beast and making it more on-highway capable. The DOT approved T63 tires offered the best trade-off for both dirt and asphalt use. The internet is rife with examples of Honda XR650R motorcycles morphing into supermotards and dual-sports. In fact, despite its reputation as the ultimate Baja racer and "off-highway" desert bike status across North America, the Honda XR650R reached much of the global market in semi-street form. Draped in highway amenities and trim for Europe and Australia (detuned substantially for the Down Under market, making it all the more street worthy), the XR650R has the ability to serve incredibly well as a dual-sport. My cycle was purchased in just that form, the previous owner was Texas based and had added a Baja Designs conversion kit and DOT tires. The bike was on- and off-highway legal, and I readily registered, plated and titled the motorcycle as such at Nevada. Off pavement, the Michelin T63 tires work well. DOT for the highway, they deliver on asphalt, too. Here, I test the tires at Nevada's wild horse country and later on a curving ribbon of asphalt. The Honda XR650R dual-sport conversion can deliver in both worlds! Here I was with a dual-sport platform, so why not go the next step and add the necessary cargo racks and luggage? As a highway rider as well as a dirt guy, I instinctively switched to the Michelin T63 tires for an on-highway improvement. Tested on dirt and the highway, the tires were as close a compromise as practical for both asphalt and Nevada's graded gravel roads and alkaline dust single-tracks. The next step was a leap, the choice of TCI Products' Sequoia and Borrego racks, along with TCI's skid plate and engine guard protection. Installed, there was no going back. The Johnny Campbell/Steve Hengeveld Honda A-Team profile vanished. Was this okay? Well, truthfully, I did pause for a moment. After years of selling myself on the idea of a Baja-bred desert enduro bike, to see these, admittedly, well-crafted and precisely fitted saddle bag and tail racks, hanging off the back end of a race-bred dirt motorcycle, was certainly a "different" look! This video gear and motorcycle camping gear need a place to ride! The Nelson-Rigg luggage and TCI Products racks have provided an outstanding solution. The package transformed the Honda XR650R desert enduro bike into a dual-sport that rivals the "big" adventure-touring bikes—at half the curb weight and nimble enough for single-track and fast-track desert! Once I added the tastefully designed and rugged Nelson-Rigg luggage to these quality racks, I was able to exhale. In fact, as I fitted the luggage onto the stable and sturdy TCI racks, following closely with the video cam to catch the nooks and crannies of the bags, it became clear that this is one good looking, highly versatile and rugged package! I'm thrilled with the utility of these racks and bags. Moreover, the cycle has the best of both worlds: Capability off-road yet ample suitability for short—and even long—highway riding! Click on the links to see the tire testing, the TCI Products rack and engine protection installations, and my choice in Nelson-Rigg luggage. You'll not only be impressed, if you've been indecisive about converting your pristine enduro bike into a dual-sport, this might very well tip the scale! Moses
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So, I have this Euro model XR650R project, and I acquired the bike right. As the upper engine rebuild and other restorative measures unfold, I'm starting to wonder what is a reasonable amount to invest here? The engine work and all the other parts I've bought are pushing things pretty close to $2k - and this bike can't be worth much more than that! Furthermore, I dropped nearly as much on new gear (helmet, boots, gloves, etc...) DON'T TELL MY WIFE! Cheers, David
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The Hot Cams Stage 1 cam for our Honda XR650R motorcycles sounds to be exactly what I'm after in power. In the past more power equaled more fun. That still holds true today, but to a lesser extent for me. I definitely will have to put in the Stage 1 cam if the bike shows wear in the top end anything near what yours had. It's good to know there is still more good power to be had even if I don't really need it. As far as that auto-decompressor, I only use it because that is all there is on my xr500r. It is a real pain trying to use to bump start the 500 even when it is on top of a good hill. I've been an Oregonian my entire life. I've barely moved a mile from where I grew up, but the change in population, traffic and rat race in general is extreme to the point of looking to move when I retire. I love Eastern Oregon, friendly people, beautiful country, you live in the outdoors. There are drawbacks of course or everyone would be moving there. All of my riding in Eastern Oregon is in conjunction with camping, which was in the vicinity of the Strawberry Mtns this year. I look forward to doing more exploring of the Steens and even the more remote Trout Creek Mountains someday. We generally ride out there on the remains of old jeep trails, roads that are no longer on any modern maps and sometimes I use Google earth to look for ways in and out of certain areas. My son led us into one area last year where we didn't get our bikes out for 3 days. We had to hike out cross country (I have a good sense of direction) for over 12 miles much of it as the crow flies, getting back after midnight. That was a bit reckless and won't happen again. I used the remaining bike at camp to explore an alternate route coupled with quite a bit of hiking to get the bikes out. Western Oregon as you know is a completely different climate and very different riding. We rode in the 70's out in the Burn, now the Tillamook Forest. Where we used to run in the Trask is now gated since Weyerhauser bought out Willamette Ind holdings there. We ran a lot where the Trask Mt ISDT was held, and would seldom see another rider. The best riding I ever experienced. I'm not sure where to go now. I'm trying to get 2 of my old riding buddies to ride again, One of them has an 80's TT600 and still rides occasionally, and may know of some good areas and the other still has his TT500, but hasn't started it in a very long time. Interests often change, but I will keep trying until I hear a no answer. I have never ridden the dunes, but my stepson who is into quads has been asking me to come. It is not close and finding that much travel time has not been easy. I'm interested in what you find when you dig into the 84 XR500R. It has a totally different engine than my 82 model. Did you know the 82 xr500R has a reed valve? I have been experimenting with the rear suspension on my XR500R. I've given it more sag and in doing so lowered it quite a bit. It was sprung too stiff for my weight and while much smoother than the ol BSA, I think I can make it fit me better with some tuning, but I will sacrifice some comfort for good trail riding ability. The reason I went with the 82 xr500r over the 84 XR350r was the over heating factor. I was afraid I could burn it up on slow trails in the summer heat. It has adequate power and a much better front brake, but I thought better suited to running fire roads to keep air moving around the engine. I should look into jetting but it does run smooth. I don't remember if I ever checked the plug. I'll have to do that. You can smell the heat coming off the engine when every other bike with us is normal. Greg -
At the forums Garage Photo Gallery, member "FullChoke" (Greg) responded to my photo of the magazine's 1984 Honda XR350R motorcycle. We have identical '84 XR350R motorcycles. Greg's cycle has engine heat-up problems, and this raises the issue of how to keep any air-cooled dirt or dual-sport motorcycle engine running cool enough. I'll begin with sharing our exchange at the Garage (below), followed by pointers on how to keep an air-cooled dirt or dual-sport engine from overheating. ************************************************** My comments at the Garage Photo Gallery: Moses Ludel 23 September 2013 - 02:33 PM The Honda XR350R cycle has been in our stable since the late '90s. Rick Sorensen, an A&E aircraft professional, had set up this dirt motorcycle for desert enduro riding. Rick's attention to detail, tuning and appropriate upgrades has made this one of our favorite dirt motorcycles to date. When new, the 1984 XR350R came with many advanced features, including Pro-Link rear suspension, a disc front brake and the four-valve, twin-intake and exhaust thumper engine design. The performance, dependability and flexibility of this engine has been a constant source of satisfaction. Under the most challenging conditions, including crawls through milder "rock gardens", the cycle and four-valve engine have delivered tractor-like stability. In other online forums, there is much talk about the "failure prone" and "problematic" dual carburetors on the XR350R and XR500R engines. In my experience, nothing could be further from the truth. I have rebuilt these carburetors and set them up to factory specifications, adjusting linkage and cables accordingly. The dual 26mm Keihin carburetors are stable and flexible enough to get by with the same jetting from Johnson Valley (King of the Hammers) to timberline at Nevada's high mountain ranges. Note: I jet for our base at 4500 feet elevation. The carburetors tolerate short rides to 8,000 feet and drops to 2,500 feet. That's very flexible, and though I would re-jet for extended riding at either of these high or low altitude points, these carburetors will "function" over that range. Simply put, I'm not fiddling constantly with the carburetors. The transition to the secondary carburetor is seamless, and by making sure there are no vacuum leaks, the tuning stays rock steady. Sure, EFI delivers more power and refined tuning, but these twin Keihin 26mm carburetors do work well and can be adjusted, or even re-jetted with care and patience, when you're 120 miles from a paved road. As for handling, I always ride the motorcycle that's under me. Sure, a CRF450 or XR650R could "run circles" around these earlier XRs, but that's not what I'm riding here. The XR350R can provide a great ride when handled like, not surprisingly, a tuned XR350R and not a CRF450. This logic applies to road cycles, too. I never rode our Honda Gold Wing or the BMW K1100LT like I did my two 1969 BSA motorcycles, the lightweight 650 Lightning or the 750 Rocket III. When I hopped on my youngest son's Yamaha YZF600R6 a few years ago, that was a different story as well. For this XR350R workhorse, I'm considering a dual-sport conversion kit from Baja Designs to enable highway access. We have an '84 XR500R waiting in the wings for restoration, another dual-sport candidate. Each of these bikes would weigh under 300 pounds converted, much nimbler on dirt than a KLR or BMW in any form. Nevada's new OHV permit program makes it just as sensible to opt for a DOT-standards conversion and license ("plate") an XR for dual-sport use. We carry insurance either way. On that note, expect details shortly on what direction this takes. If the dual-sport conversion route, I'll cover the steps at the magazine in an HD video 'how-to'. Moses Greg's comments at the Garage Photo Gallery: fullchoke Yesterday, 09:22 PM The1984 xr350r has a history of running hot and burning up. I think that was blamed on the new head design and the 2 carb system. Possibly the overheating could benefit with richer jetting. I know mine gets hotter faster than any bike I've owned. I haven't run it much and when it is used it has been a buddy's bike, usually run fairly slow. When compared to other bikes running over the same terrain it is noticeably hotter. For that reason I run a full synthetic oil, hoping for more protection with a higher boiling point. The front disc brake is a very nice feature, best thing about a very good bike. Greg ******************************************************************* How-to troubleshoot an air-cooled motorcycle engine overheating problem: As for overheating, let's start with a systematic troubleshoot. First and obviously, the engine cooling fins must be clean with sufficient air flow. Also, a four-stroke engine does not like to idle for extended periods in still air. This even applies to liquid cooled dirt and dual-sport motorcycle engines. (There are constant internet discussions about overheat, even on models like the liquid cooled XR650R and others.) Two-strokes with premix fuel have less tendency to overheat, though heat can still be an issue. When we ride extensively in the desert during hotter weather, I'm always conscious of air flow. After a good high speed streak or even picking through basaltic rock flows, my Honda XR350R remains "reasonably" cool. I'll let the engine idle for just a moment to help stabilize temperatures before shutting it off. We do crawl in stand-up-on-the-pegs type challenges, one location in particular is at high altitude. This engine has never reached critical temperatures. Your use of synthetic oil can help, too. Running cool at high altitudes is in part what you suggest. Proper jetting for sea level to 4,500 feet, then running the engine at 7,000 feet, makes the fuel mixture richer. I've never fouled a spark plug or experienced blubbering or unstable operation with these richer mixtures. In my experience, jetting is not that sensitive on these four-strokes, they are way more flexible than many give credit. Main jetted for best performance at 2,500-5,000 feet (our typical high desert country), this same engine has run flawlessly from 2,300 feet on the floor at Johnson Valley, CA to nearly 7,000 feet—without a re-jet. Of course, if the engine were operated consistently at 6,000 feet or higher, I would re-jet. Keep the jetting within a reasonable range. Read the spark plug color after a hard, open throttle run and prompt shutdown! That's the main jet's realm. If anything, jet slightly rich. In current jetting, my XR350R can run at sea level without burning a hole in the piston. Again, if I were to run the length of Baja, I would jet for sea level to 4,000 feet. Never jet so rich that fuel can wash oil off the cylinder walls nor so lean that the valves and piston are at risk! Learn to read the spark plug. Often overlooked is the importance of proper valve clearance. Valves adjusted too tight will cause engine overheating and also lower compression. Unseated valves lead to valve face burnout and seat damage, too. Adjust valves to specification, and also adjust the decompression lever and kick start cables. This is a big part of maintenance on the XR350R, the XR500R and similar Honda dirt bike models. The auto-decompression camshaft design eliminates the kick starter cable on later XRs. However, the manual (handlebar) decompression lever adjustment remains very important on every one of these models. On the XR models with dual carburetors, folks need to get over the idea that these engines never run right. Actually, this myth is helpful to those of us who value the dual-carburetor era, Pro-Link models—you can buy them at bargain prices! A common mistake is for the carburetors to be sync'd improperly. There is a very clear adjustment here, which I can share if necessary. Be aware that these carburetors do not open simultaneously! The linkage is actually "progressive", with a lag stage as the primary carburetor provides a smooth idle and light tip-in air/fuel flow. Then the secondary carburetor (which has no idle mix screw) comes into play. Think of this like an automotive engine with a progressive four-barrel carburetor or multiple carburetors. Adjust the cables and the staged throttle linkage to specification. These engines will start readily and run fantastically if the jetting, float level and needle settings are correct! General footnote: Current ethanol fuel wreaks havoc on motorcycle carburetor passageways. Do not leave the bike parked for long periods with fuel in the carburetor bowls. Shut the petcock, and with the bike upright, burn fuel until the engine stalls. Fuel standing in the bowl will clog jets, it did mine. The immediate symptom is an unstable idle and poor low throttle response. (I ended up rebuilding both carburetors after letting the cycle sit for too long with "winterized" and "Ethanol" mix fuel in the tank and bowls!) Use a fuel stabilizer additive, this can help for shorter storage. Long term, drain the fuel tank and the carburetor(s). Without stabilizer, fuel can become stale and worthless in months, depending upon the climate. Air/fuel flow and ratio are a critical part of air-cooled engine performance. Keep the air filter clean and oiled properly, whether stock type or aftermarket. A clogged cleaner element will make the engine run rich or stall, much like leaving the choke on. Also, when considering a lean fuel mixture, always take air leaks into account. Air leaks on the manifold side of the carburetor(s), between the head and carburetors, can lean out the fuel mixture. Check for leaks at flanges and junctions. Using a can of spray carburetor cleaner or WD-40, spray a fine mist at flanges with the engine idling. This can quickly turn up an air leak as the engine speed flares up or changes. Avoid spraying at high heat areas that can ignite the spray! Once you've worked through the intake side, make sure there are no exhaust restrictions. I have a "tunable" SuperTrapp exhaust end that is set up with the right number of discs for proper backpressure. I periodically remove the disks and gently bead blast the carbon away to keep tuning accurate. Improper exhaust backpressure or clogging can be a major source of overheat on a motorcycle engine. After fuel mixture/jetting, carburetor sync'ing, air leaks and exhaust restrictions and tune, there is the ignition spark and timing. Of course, spark must be adequate, and the spark plug should be the correct heat range, especially on an air-cooled engine. A "hotter" plug can be serious trouble if not in place for a good reason. Hotter spark than the stock Honda ignition (in good condition) is rarely necessary. Note: The compression ratio is higher, so you also need to run better octane fuel, especially at lower elevations. This may not be true for high altitude. I can run 87-octane in the XR350R at 4,000-8,000 feet because the atmosphere effectively lowers the compression ratio. I am not as flexible with the Honda XR650R at 10:1 compression and a bore size within 0.060" of a 327 or 350 cubic inch Chevy V-8! If you're at a lower elevation with high compression, spring for 91-92 octane fuel. This helps prevent detonation/ping, overheat and stress to the engine. For an XR500R, XR600R or XR650R, I would run 91-92 octane all the time. The last item on our checklist is spark timing. Either retarded or over-advanced, spark timing error can kill a motorcycle engine. Check the spark timing from idle to full-advance at speed. Make sure the timing advance is set properly. You can test with a conventional timing light or a light with built-in advance, this is not rocket science. I can help cast light on the procedure and expected results. With an electronic ignition, spark timing either works or it does not. If a motorcycle is old enough to have a mechanical spark advance mechanism, like our BSAs of yore, a sticking or defective spark advance mechanism can cause overheating as well as performance problems. Of course, there are overheat causes unrelated to the engine, like too much friction in the gear train or binding brakes (a sticky front or rear brake caliper, brake shoes dragging or warped/defective rotors and drums). Wheel bearing resistance, low tire pressure or chain drag can also overheat an engine. Check for resistance with the motorcycle wheels and tires lifted safely off the ground or floor. This is a place to start, and I am happy to continue this discussion. Glad that FullChoke triggered this topic, that's what these forums are all about! Moses
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The burgeoning interest in overland motorcycle travel and dual-sport conversions has many incentives. Aside from the relatively inexpensive nature of motorcycling when compared to four-wheeled travel, there is also the unique sensation of open-air, two-wheeled adventure, traveling overland to far away, dirt road places...Every dual-sport enthusiast has his or her idea of the ideal motorcycle adventure. Mine happens to be twofold: the Himalayas (specifically Bhutan, Nepal and Tibet) or Mongolia! Oh, then there's also the Silk Road... To even consider such a grand scale trip would require solid planning and the right equipment. Motorcycle stowage space is limited, and fuel is scarce at distant places. Fuel capacity is always a concern, often remedied with an aftermarket tank during a dual-sport conversion. Camping gear must be compact, light in weight and effective. Despite space limitations, your physical needs will be the same. Quality, life-preserving equipment is the order of the day. This forum community is for those of us earnestly outfitting for long distance travel to remote places. Even shorter jaunts across a remote mountain range, a desert like the Mojave or Black Rock, Death Valley, Central Nevada or whatever, requires provision for the temperature extremes in an arid climate. I've lived at high desert and higher altitudes the majority of my life, so temperature swings of 40-degrees F or more in a 24-hour cycle are not foreign. I've worked outdoors at -20-degrees F with wind chill added from there. I know what materials are life saving in extreme cold—whether running heavy equipment at Winnemucca in December or riding a motorcycle over the Sierra in the late fall or spring. Enjoy this Dual-Sport and Dirt Motorcycle Equipment Forum, it's a community where we can all share our enthusiasm and insight for safely and practically traveling to remote places!—Moses Ludel
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There's a loyal following for many of the "adventure-touring" motorcycles, cycles like the KTM 990 Adventure or BMW F800GS and 1200GS. On the other hand, many dirt bike riders are now turning to "plated" dirt bikes, bridging the gap between asphalt and a desert enduro bike. Do we need to draw a literal "line in the sand" about what makes a legitimate off-pavement motorcycle? I have ridden this '84 XR350R for nearly two decades and also own an '84 XR500R. Despite growing parts availability issues, these bikes are failsafe mounts for open desert riding. For the magazine's 2012 King of the Hammers coverage, I took the XR350R to Johnson Valley. A dual-sport conversion for plating this cycle has been considered, if so, highway riding would be limited. I would not hesitate to take this machine over the Rubicon Trail and often ride to remote desert and mountain reaches! For decades, I have ridden dirt bikes (primarily Honda XRs) in single track woods and open desert. I have ridden on asphalt for over half a century, beginning with motorcycles like a vintage BSA 650 Lightning, a Victor 441 and a Rocket III 750. More recently, my highway cycles were an older BMW 80GS boxer, a Honda GL1500 Goldwing and a BMW Kll00LT. Despite my respect for high end adventure touring motorcycles like the KTM 990 Adventure, I have an opinion and will share it: Serious dirt bike riding requires a true dirt bike—adventure-touring bikes, even the best of them, are no match for a true enduro motorcycle off the pavement... KTM, Yamaha, Honda, the Christini AWD DS and others now offer serious dirt motorcycles that meet DOT and EPA highway requirements for street legal use. (I do not include Kawasaki's KLR among "lightweight" dirt plated bikes, as the beloved KLR650 has crept from 325 pounds to a porky 432 pounds in recent years!) As an open desert and single track woods rider, I am drawn to these bikes. Unless a lot of asphalt is in the plan, I believe a true dirt bike with D.O.T. approved knobby tires is the best mount for serious off-pavement use—and moderate distance road riding... Contemporary dirt motorcycles with minimalist D.O.T. equipment weigh under 300 pounds. An adventure touring beast can run over 500 pounds, in particular a road-ready machine like the BMW 1200GS. While I truly appreciate the handling, safety and highway agility of a BMW motorcycle, jerking a 525-plus pound motorcycle out of a sand trap is not my idea of a good time...For those who do think of this as an "adventure", I heartily recommend Warn Industries' new line of portable winches designed for adventure touring motorcycles. Admittedly, the plated dirt bikes are minimalist and intended that way: A KTM 500 EXC tips the scale around 250 pounds...These machines remain true enduro motorcycles. Slightly higher in weight is the AWD Christini, coming in at 288 pounds with two-wheel drive traction, a worthy trade-off and ready solution for those sand traps! Before adventure touring motorcycle aficionados boycott this forum, let me add that I have owned a BMW 80GS and a BMW K1100LT. Each was terrific—on the highway. "In the day", I owned BSA motorcycles, including a 441cc Victor, and despite the Victor's lighter weight, it was a stodgy motorcycle off-pavement. Today's dirt motorcycles would run circles around a Victor—or any other vintage "enduro" or "scrambler" motorcycle with vertical rear shock-coil springs! So, I'm raising these questions: 1) Is there a place for adventure touring motorcycles off-pavement? 2) Can a rider on a lightweight dual-sport with DOT knobby tires survive much time on the asphalt—if so, how much? What are your views on each motorcycle design?...Join this forum and share your off-pavement experiences and preferences! Moses
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Building a motorcycle engine for reliable performance begins with careful assembly work. The Honda XR650R project came under the close scrutiny of an HD video camera, and the result is the 49:37-minute streaming video rental at Vimeo On Demand. Following the build, proper break-in of the engine is crucial. During assembly of the XR650R top-engine, care was taken to lubricate critical parts for the initial engine startup. This included lube on the piston pin, rings, valve stems, camshaft, valve tips and timing chain—as illustrated and detailed in the video. Lubeguard Assembly Lube, Permatex Ultra-Slick Assembly Lube and Lucas break-in oil with zinc were each used accordingly. The importance of zinc additive during break-in cannot be overstated. When a cylinder has been honed precisely like the work performed at L.A. Sleeve Company, piston ring seating is less of a concern than the camshaft break-in. Ring seating is still important, and I will describe my technique for ring-to-cylinder wall break-in: To begin, I use a non-synthetic oil that will provide enough friction to actually seat the rings. Synthetic oil often has too much of a protective film to allow necessary friction. After break-in, I will change to full-synthetic oil and dramatically decrease ring wear by providing an extra friction barrier or film between the cylinder wall and rings. Ring seating can be dramatically enhanced by smoothly accelerating the engine and decelerating the engine. Heavy throttle for sustained periods should be avoided for an initial timeframe (at least an hour of operation or 60-100 miles of road use). When you decelerate the engine, the piston rings push out against the cylinder wall. As noted in the video, the top compression ring for the Honda XR650R has a gas ledge machined on its upward facing, inside edge. This raises ring pressure against the cylinder wall, especially during acceleration/deceleration cycles. This increased pressure quickly seats the rings. Caution: A sure way to prevent rings from seating is repeated hard acceleration without any deceleration cycles. Gradual acceleration, limiting peak rpm and regular deceleration cycles get the best results. Camshaft break-in is highly significant. Damage to a new camshaft's lobes during break-in can occur quickly. The absence (deletion) of zinc from current motor oils has made this issue even more critical. (I discuss this at length in response to a Jeep 4.0L flat tappet camshaft and oil question here at the forums, read that information at the topic link.) On the Honda XR650R engine, an aftermarket camshaft from Hot Cams came with very specific instructions on initial startup and break-in. I include those concerns in my camshaft startup and break-in approach: During upper engine assembly, Lucas break-in oil with zinc was added to the oil (poured over the camshaft) prior to startup. The amount used was based on the product's instructions, and I reduced the quantity in proportion to the quantity of oil in the Honda XR650R lubrication system. At the first startup, the engine was run at 2,500 rpm immediately after picking up oil pressure. On the motorcycle lift and strapped upright, the motorcycle's engine was cycled between 2,500-3,000 rpm with a large electric fan in front of the cooling radiators for the first 20 minutes before idling down to 1500 rpm. (I used an infrared thermal gun to monitor cylinder, head and exhaust header heat this entire time.) After the initial 20-minute run on the stand, the initial road/trail miles involve a cycling speed between 1400 rpm (idle) and an estimated maximum of 3,500-4,000 rpm (no tachometer on this dirt bike). I run for 20-30 minutes at a time, varying the road or trail speeds, then cool the engine completely before repeating the cycle. Make sure that your lighter on-road or on-trail use provides sufficient cooling air to the radiators and cylinder. Earlier morning or cooler evening rides are helpful. Avoid idling for extended periods, and avoid over-revving the engine. I avoid redline shifts for at least the first 100-150 miles or 1.5-2 hours of operation. Considering the operating speeds for a four-stroke motorcycle engine compared to an automotive engine, three hours (approximately 200 miles) of concentrated effort to break-in the camshaft properly should be sufficient. Rings should be sufficiently seated now...At this point, the oil should be drained warm and thoroughly; I switch to synthetic oil now. Note: During this oil change on the XR650R engine, I will remove the frame (down tube) oil screen (not the inside-engine screen) for inspection and cleaning. A new oil filter is mandatory; inspect the removed oil filter for unusual debris. In the road test video, I'm on the throttle but not redlining. I don't baby (never "lug") or abuse (do not over-rev or throttle hard) an engine during break-in. Constantly monitor engine temperature and avoid overheating or extensive idling. The Honda XR650R showed no signs of "blue smoke" (ring blowby or valve guide seepage) from the very first start onward. You should not see blue smoke or significant oil consumption if the cylinder has been honed properly, the rings were installed correctly and the valve guides are sealing. By 200 miles or 3 hours of operation, a motorcycle engine should have sufficient break-in to no longer be a critical concern. As long as oil consumption (ring blowby) does not occur with the switch to synthetic oil, the engine is ready for reasonably "normal" use—whatever that means for your riding style. For the properly built engine, with correct break-in, a quality synthetic oil will determine the lifespan of the rings, valve guides, timing chain, camshaft, rocker arms, engine bearings, piston/pin, and other critical moving parts. Wear is greatly reduced by the use of synthetic oil. Unlike an automobile or truck engine, wear will be much more significant on a motorcycle engine that operates consistently above 3,000 rpm. Wear is all about piston travel and valve opening events, and synthetic oil can make a difference here. Moses
