CRF450R snow bike build

[53HiHood]

I finally picked up a Timbersled Mountain Horse snow bike kit for my Honda just last month. I starting prepping my bike for install but decided to check my valves since it had been a couple races since last checking them. The intakes were both out of spec. Time for new valves and seats. I bought the bike new in '05 and hadn't had to do any engine work to date so it's impressive that the oem Ti valves lasted this long. Millennium Technologies in WI did the head rebuild. I opted to stick with Ti valves over SS due to weight. MT replaced the seats with a copper beryllium seat that will extend the life of the Ti intake valves. The cylinder was stripped and had a new Nikasil coating applied followed by their diamond hone. I had read about L.A. Sleeve in the past but it totally slipped my mind when it came time for the rebuild. Next time! A racing buddy insisted I only use a Wossner piston kit, it's a really nice piston. I just finished assembling the engine 2 nights ago and finished installing the MH kit and a new TT hour/tach and a Koso temp gauge last night. I ran two 5 minute heat cycles and had no surprise leaks or sounds. Two twists of the throttle and she fired on the first kick.(I did slowly kick through about 4 or 5 times to get oil circulated around before the initial start-up)

I replaced all of the carb vent lines with shorter lines after rebuilding the carb. I ziptied them all together and then ziptied close-celled foam over them to keep snow/ice from obstructing them. I have a one-way filter on the end of the lower engine vent tube for the same reason. The kit comes with an Outerwear pre-filter but I did not install it, rather I blocked all of the intake box openings with more closed-cell foam. Due to it now being spring just about and the days of deep powder riding numbered, I did not make engine shields to keep the engine warm(hopefully the t-stat will keep operating temps up) or install any sort of carb heater.

[Moses Ludel]

Yes!  Great bike and great work, 53HiHood...The head work sounds right on for contemporary metallurgy.  (Titanium valves with copper beryllium seats should work very well together.) , Nikasil will hold up well with proper air filtration and seal.  It's a real testimonial to your service routine, and riding technique, that this is the CRF's first top engine build...Congrats! 

Cannot over stress the importance of filter seal, my pre-owned XR650R had only "1000 miles" on the engine and needed a top rebuild due to poor seal on the aftermarket air filter during the PO's watch.  All worked out well; however, I couldn't ride the cycle from date of purchase for the next several months, busy with the work, sublet machining and usual time constraints, including creation of a Top-engine rebuild instructional HD video rental at Vimeo On Demand!  Delayed gratification, just glad to have a BRP in 'as new' running condition!  Better than new, actually, I like the Stage I camshaft from Hot Cams...

You're bucking the warming weather trend, too.  Trust you'll get in some snow riding before the spring thaw...Weather reached 70 degrees F at 5,000 feet elevation yesterday...I took a 45-minute ride on the XR650R...Will do so again today on the XR350R before our winter/early spring pattern returns.  We need way more snow in the Sierra Range!

Let us know how the Timbersled Mountain Horse kit works.  This is one way to ride year 'round...looking forward to discussing our bikes.  Is the CRF450 plated?

Moses

Edited February 26, 2016 by Moses Ludel

[53HiHood]

The air filter set up on these bikes is top notch, virtually impossible to have any poor sealing issues other than installation error. I change the oil probably way too often, which I need to stop doing, and the air filter is changed regularly. When they are only $10 there's no excuse to have a dirty filter.

Tomorrow will be the maiden voyage for the bike with kit. Going up to Mt. Baker, no lack of snow up there. I think the ski area had the first or second most snowfall again this year. The snowpark locations can make it tricky though if they are too low in elevation or people try to drive cars past the closure.

My bike was plated, at one point the 450 and my old CR250R were plated. Nothing but trouble to be had on that 2T. Fun bike.

[Moses Ludel]

Fun!  Keep us posted on the snow venture...Wow, this is exciting...

The CR was a beast.  I rode one years ago with my eyebrows raised.  Your CRF450 makes a lot more sense for the kind of riding you like.  The CR250R was incredible but purpose built.  Here's a nice tribute:  http://dirtbikemagazine.com/news/hondas-greatest-bike-the-cr250r-two-stroke.  I'm sure your real world experience included moments that were not as romantic.

Why did you drop the plate on the 450?  Not enough pavement riding to justify?  I ride the XR650R 60% or more highway, my original thought was 20/80, primarily dirt riding, but the cycle is so fun to ride and versatile that I can't leave it alone.  I do need a Seat Concepts pad upgrade on the OE seat.  It's agonizing to ride distances on asphalt.

Moses

 

 

 

[53HiHood]

I can still register the bike, but I haven't had the DOT gear on it since my first 24 Hours of Starvation Ridge race back in 2010. My work commutes are always long and I always had another motorcycle that was primarily pavement oriented.

I had a pretty good day on the timbersled. There were some bare gravel spots on the way out of the snopark but my off road wheel kit got me through most of it. The first hour or so was really difficult. I hadn't been on the bike since a bad crash in 2014, and the ski really likes to grab when you're following tracks. Once I decided to pick my own route it was so easy, and fun. The sleds had trouble following without getting stuck. And surprising I didn't get stuck once today. I could stop on a hill and that bike would just go. We found some great open timber and meadows to play in and I'll say that was some of the most fun I've had on a bike I think. The only negatives from today were the fork springs being too soft and my air fuel mixture screw falling out, which fortunately happened as I was going down throw the trees. I noticed the rpm's drop and then the bike died. I jumped off and looked over the carb and saw the screw and spring sitting on the bottom end. Lucky! A missing o-ring was the culprit there. As far as the springs, I'll have to find something stiffer. Ideally I would like to find a second set of forks that I could set up for the kit.

[Moses Ludel]

Looks like a lot of fun!  Understand it would be more stable in fresh snow and not locked in others' tracks, unable to climb out...Glad you found the idle mixture screw...How does that four-wheel cradle/dolly work?  Is that "the kit" you use for dry stretches, or do you reinstall your front wheel?

Plenty of snow at the top, let's cross fingers for more.  We could use six more weeks of snow storms in the Sierra Region and its watersheds.  Another balmy 70 degree-F day at 4400 feet today.  Moab EJS will likely be springlike mid-month.

Thanks for sharing!

Moses

P.S.:  Great scenic photos!  The snow bike against the peak is exciting, tracks in the background!

Edited March 1, 2016 by Moses Ludel

[53HiHood]

The wheel kit is used to get from the sno-park to the snow when the snow starts going bye bye or when the groomer hasn't moved the sign to allow us to drive to the snow. It works pretty darn well for something I fabbed up real quick friday night. It is bulky though and I might look at other lighter options. I placed an order with Cannon Racecraft for stiffer .58kg/mm fork springs and I'm hoping to find some used forks to install them in so I won't have to mess with my race-tuned suspension. There's not a lot of info out there for properly setting up snowbike suspension, a lot of people doing different things, a lot of temporary fixes. The bigger suspension shops are figuring it out though and I was able to get some good direction for my bike. We'll see how it goes.

[Moses Ludel]

You're getting major snow in the NW now, we're expecting a Sierra storm this weekend...You should get more tuning and riding underway this year!

Moses

[53HiHood]

Haven't posted in awhile about the bike. I did end up building snowbike specific forks with stiffer springs, and after getting into them a lot deeper than I would like, they work great. No more bottoming. I've been out multiple times this winter already and the bike is running great. I made engine covers to keep operating temps up in the 180-215 range, a lot of riders don't understand the importance of this and end up with fuel in the oil and engine damage.

[Moses Ludel]

53HiHood...Welcome back!  Know you're busy with career and projects...The update on the Honda CRF450R motorcycle snow conversion looks like great fun and an alternative to cabin fever!  We're getting your storms and similar winter, plenty of snow building in the Sierra.  8.5" of snow here overnight at our high desert east of Reno/Sparks, storms keep coming.  The Portland Area has been slammed.

Good year to have a snow converted motorcycle!  Very good point about needing to raise the engine's coolant temperature.  Your bike is still carbureted like my XR650R.  That could raise havoc like you share with a cold engine not burning fuel properly.  Raw, unburned gasoline will wash the cylinders of oil and quickly cause damage or even engine seizure.  

Good move with the panels.  Everyone should take heed here.  My XR650R would have trouble reaching thermostat temp in our current cold with chill factor; it's still in dirt riding mode and parked comfortably until Moab EJS.

Amazing that you can track in deep powder like this!  How long does it take to make the switch back to dirt/trail mode, including the forks changeout?

Moses 

[53HiHood]

It's a lot of trial and error with the engine jackets. I made mini covers for each radiator to fine-tune my temps for different scenarios, like if I'm riding down a groomed trail, climbing hills, or carving in powder. The switch could be done in under an hour I'm sure. I'm good about getting side-tracked so I think I spent a couple hours at least this last time because I was screwing around with other things on the bike.

On the particular day I took that last picture I posted the snow was coming over the seat when I was going slow. Getting stuck was easy that day, but getting one of these unstuck is a much easier task than a snowmobile.

Last week was great, blue skies every day. I found a little 20' drop early in the morning which resulted in a fender trim. Tough to not get distracted in such an incredible place but lesson learned.

[Moses Ludel]

Breathtaking backdrop, I can see why you want access, and what better way!  Also helps offset cabin fever, right?  Plenty of cardio and resistance exercise, too...We all enjoy your photos!

[53HiHood]

I didn't notice how loud my bike was getting until someone mentioned it up on the mountain. I've never repacked this muffler so I got it done, gotta protect our riding areas. I also checked my valves tonight after another oil change. At 16 hours the exhaust valves were unchanged but the intake valves were extremely out of spec. I re-shimmed them at 0.1 hours following the heat cycle break-in and got them both right at spec at 0.16mm. They were at 0.02mm and 0.00mm. How could they have changed that much? All the hours were riding snow, not dirt. So I don't see that it could be wear from dirty air. Could the new seats not have been seated in the head properly? I'll have to call the machine company to get their thoughts. I'm interested to hear thoughts too Moses.

[Moses Ludel]

You're meticulous in your approach, few have the valve shim assortment without a serious interest in doing this task correctly...

I'm assuming that you brought the piston and flywheel timing mark to TDC on the compression stroke without overshooting TDC and backing the crankshaft up.  As a general rule, the valves must be checked at the correct point without interference from an auto-decompressor.  This is not a problem on my XR650R engine, I switched to a HotCams Stage 1 camshaft, which eliminated the OEM start decompressor altogether.  I use the manual compression release lever for start-up piston tick-over.

Note: Always bring an OHC engine to TDC slowly.  If you overshoot the TDC mark, either back up the flywheel 180-degrees and bring the piston back up again, or continue rotating the engine all the way through its normal crankshaft rotational direction until the piston reaches precise TDC in the direction of normal crankshaft rotation on the compression stroke.

Concerns would be the auto-decompressor, re-torquing the head after the valve adjustment or temperature differences.  Was the engine completely cold when making the original check and this one?  If so, and barring the other possibilities, the zero clearance and tight clearance measurements are a concern.

If the auto-decompressor is not influencing the valve clearances and rocker arms on this adjustment when compared to your first valve re-check, you likely have a noticeable amount of valve seat recession.  The valve stems are riding higher than the last time you checked the clearances.  Either 1) the valve heads and faces have pocketed, 2) the valve seats are receding from wear or 3) as you hint, there is the rare possibility that the valve seats have either pressed or pounded into the head further.  

If the seats were not fully in place initially, valve spring pressure and heat could seat the valve seats.  If the seats are now tightly in place, you could go another round and check for continued gap changes.  Or, if you suspect valve pocketing or seat recession wear, you would need to remove the head, disassemble and inspect...

Moses

[53HiHood]

I talked with my racing buddy that also builds bikes about it again today. He said that since I reshimmed after running through heat cycles at idle rpm's and didn't recheck after properly loading the engine, I'm now seeing the actual seating of all the new parts. Maybe the Ti valves stretch a little during break in. He did tell me to go ride and recheck them again to see if the clearance changes or if they stay the same. Sounds logical. I guess we'll see.

[53HiHood]

Put a couple hours on the bike at Mt Baker today and it ran really great. Idle better, felt a littler more responsive off the bottom, and sounded better. Checked the valves just a bit ago and zero change in clearance. Checked the plug after doing one size on the main and it looks like what I have been taught a perfect plug should look like, cardboard brown.

The darker plug was before, lighter after. The darker plug was uniform in color on the porcelain, the lighter plug only had color on the top half. Am I reading my plugs correctly? Which one is actually better?

[Moses Ludel]

Lower plug looks very good, complete burn and good coloration. Upper plug could be the result of irregular compression from the tight valve clearances.  Presumably, there's no damage done to the valves from tighter clearances.

What is your valve check procedure?  Explain the heat cycling and at what point you check the clearance.  Seems you've overcome an issue here. Has fuel been the same?  How many hours on the upper plug with the tighter valve setting?

You're varying altitude and at some high elevations.  Jetting would be awkward with a wide range of altitudes...Not running "fat" or excessively lean, according to the plugs.  What octane fuel?  Your fuel source over time?  Any fuel additives?  

Moses 

[53HiHood]

I think the valves are fine, if there was any excessive wear from tight clearances it would be to the cam lobes or lifter buckets I would think. No noticeable irregularities.

The valve check procedure for this bike is every 15 hours. Fairly simple; pull plastic shrouds, tank, seat, and valve cover. It's hard I would think to not get it onto TDC because it's the only place that there is free play in the exhaust rockers.

The heat cycling was just two 5 minute idling periods with cool down in between to help seat the new parts. I checked the valves again at that point and adjusted the clearance. I should have checked them again after my first ride where the engine was put under load, as they do at the factory with a dyno run. I would have found they needed re-shimmed. I'll do that in the future with my rebuilds.

The plug had 16 hours in the first picture and almost 18 in the second, it was installed during the rebuild. It's the same plug in both pictures. The only change made was dropping one size on the main jet.

I always run premium (non-ethanol when I can find it) and as fresh of fuel as possible. It's a 12.5:1 C.R. engine so quality fuel is key.  I treat my fuel with Sta-bil and sometimes I add Seafoam to a tank to keep the fuel system clean.

[Moses Ludel]

Your slightly leaner main jet helped dramatically, likely due to the altitudes where you're riding under load.  Sounds like you have the valve setting in check.  Tight valves, had they been excessively so, would damage the valve seats and faces.  Poor combustion causes carbon buildup, and air-fuel charges escape from the unsealed cylinder.  Tight valves also create heat.  Sounds like you're okay this time around, the valves were likely not unseated at full closing, plus titanium is resistant to heat.  No sign of carbon fouling on the spark plug...Glad you can move on.

I choose to run somewhat fatter jetting on the XR650R, it's a tractor with gobs of low-to-mid range power, more tolerant of forays to higher altitudes without an immediate need for a jet change.  I jet to an optimal 2,000-2,500 feet elevation.  We live at 4,200 feet where I ride from 4,000-6,500 feet regularly.  I can run the XR650R from sea level to 7,000 feet somewhat fat at altitude, without risk of fouling or fuel washing the cylinder—or the other extreme, leaning out excessively.  The XR650R AC (California) ultra-lean factory 125 main jet for sea level was a death knell for these engines; 175 was the norm outside North America, and I run a 172 main.  A 165 main would be a consideration if riding above 5,000 feet for extended periods.  For reference, I have an L.A. Sleeve Company iron-chromoly cylinder liner and milder HotCams Stage 1 camshaft.

If you're curious about my tuning strategy, it's familiar to most XR650R owners though I take my riding range and style (single track to open desert) into consideration: 

 

Your CRF450 at 12:1 compression is not tolerant of this kind of wide range jetting, proof being the single jetting size change that has made such a difference.  I do run a Pulstar spark plug which offers better ability to fire through a richer mixture...While richer mixtures have a cooling effect, if the mix is too rich, fouling or incomplete combustion becomes equivalent to retarding the spark timing.  Power drops accordingly...This is not as prevalent an issue on 4-strokes as 2-strokes, one reason I prefer 4-strokes.  They have a much more "forgiving" nature when riding at varied altitudes!

Moses

[53HiHood]

[Moses Ludel]

Wow, a big WOW!  What's the elevation?  Location?  What peaks are in the distance?

Beautiful!!!

[53HiHood]

That's up on Mt Baker, around 4500'. This is looking south at the Cascades.

[Moses Ludel]

Fantastic!  We lived at Eugene/Springfield and Oakridge in the Willamette National Forest region for years.  The entire volcanic chain is phenomenal.  For those unfamilar with Mt. Baker and why you're seeing so much snow there this year, here's a quip from Wikipedia:

"After Mount Rainier, Mount Baker is the most heavily glaciated of the Cascade Range volcanoes; the volume of snow and ice on Mount Baker, 0.43 cu mi (1.79 km³) is greater than that of all the other Cascades volcanoes (except Rainier) combined. It is also one of the snowiest places in the world; in 1999, Mount Baker Ski Area, located 14 km (8.7 mi) to the northeast, set the world record for recorded snowfall in a single season—1,140 in (2,900 cm).^[12]"

Here's the rest of the story and a photo of blue sky with a huge mantle of snow:  https://en.wikipedia.org/wiki/Mount_Baker.  You're fortunate to have access and just the right mode for getting there!

Moses

[53HiHood]

It's an incredible place.

I rechecked the valves again after that last ride, which was probably the hardest I've ridden the bike since the rebuild, and again zero change. I pulled the plug again and it's just slightly darker. I was on the throttle a lot more that day and higher in the rpm's. I'm more comfortable with the color, it's in the middle of the two plug pictures in my earlier post. And the bike really feels like it has more power. My buddies KTM 450 can't keep up and won't climb near as well as my Honda. Obviously Honda makes a far superior motorcycle, but I was surprised at how much his bike struggled. Ride Red!

[Moses Ludel]

Yes, Ride Red, indeed!  And what a place to ride...Glad the plug looks even better, you're covering a range of altitude, and at 12:1 compression, a plug gets sensitive to air/fuel mix.  You're able to run this carbureted bike like an EFI model.  Great tuning effort!  The temperature control with your radiator panels was a very smart move...That helps combustion.

Moses

[Moses Ludel]

53HiHood...Saw the latest issue of Traction eRag and thought of your Honda snow bike.  This irreverent, amusing magazine from Canada is a free subscription.  The magazine is flip page, enjoy it:

http://www.tractionerag.ca/issue37/html5/index.html?page=1&noflash

Moses

[53HiHood]

The guy on the cover is a local, rode with him once, except he decided to show up on a sled instead of a bike. I haven't been out much, poor visibility and tons of side projects have kept me off the mountain. I did pick up a new bike in the mean time, 2007 Yamaha YZ250.

[Moses Ludel]

53HiHood...The YZ250 will be fun as the weather turns to spring...I did a video of my oil filter cover bolt thread upgrade on the Honda XR650R.  You'll find the info interesting and worth filing for your motorcycle and 4x4 projects.  I've also used a Time-Sert® upgrade on the spark plug threads and swing arm adjuster threads.  Check it out: 

Thanks for adding info at Kyle's disc brake conversion master cylinder topic.  Helpful!

Moses

[53HiHood]

I'll have to remember the time-sert®, looks like an easy and permanent fix for a bike.

[53HiHood]

I'm in the process of building a new engine for my snowbike. The bike runs great in stock form but I find myself shifting back and forth between 3rd and 4th gears a lot and I think a little more torque will allow me to pull that higher gear. I did only have 35 hours on the new top end but the bottom end was still stock and untouched. I'm setting the cylinder and piston aside for future use. I didn't find any abnormal wear in the top end or bottom end. Crank and transmission look great, but my con rod small end is at the spec limit. 

I sent my crank and head in to millennium technologies for a full crank service ( new rod, trued, pin welded) and the head will receive a CNC valve job and CNC race porting. MT now manufactures their own big bore kits in house and I have chosen the +4mm overbore. Their nikasil coating is lifetime warrantied and they carry only the best forged pistons. I will be installing HotCams stage 3 camshaft to compliment to race porting and larger bore. Since my intent with this engine is to build more hp and torque, it will be built to run on race gas. I can't wait to get everything back together and get out in the snow.

[Moses Ludel]

Beautiful project...Sounds like a thorough build-up...The upgrades are impressive.  

The small-end of the Honda connecting rods remain a mystery.  My XR650R thumper has the same arrangement as your 450, and it's simply a matter of time before these lower ends need rod attention.  What's the "permanent" fix here?  Is a better rod available or does that lead to premature pin wear?  What's the MT solution?

This is carbureted, right?  Will the engine be more sensitive to altitude with the C.R. bump and other mods?  While the HotCams Stage 3 camshaft was designed for open desert/Baja racing, is this okay for a ski-conversion bike?

On that note, your friend's XR650L could benefit from a HotCams Stage 1 upgrade.  I'm thrilled with this on the XR650R and even more thrilled to have eliminated the factory auto-decompressor kick starting mechanism. 

Does the Stage 1 XR650L camshaft eliminate the auto-decompressor for kick-over?  I use the handlebar manual de-compression lever/release to 1) pinpoint TDC on the compression stroke and 2) bring the piston over TDC just slightly.  Release the lever and kick through with full compression.  Tuned properly, the engine should start first kick 90% of the time—two kicks the other 10%.  Unheard of, supposedly, for an XR650R!

[53HiHood]

There are multiple aftermarket sources for con rods and I believe some press a bronze bushing into the small end. MT installed a Wossner rod. With this new top end being a big bore I'm not sure if an OEM rod would be the best option. But for all I know they could all be very similar.

The bike is carbureted. I'm staying at the factory compression ratio of 12.5:1 and I'll be running 50/50 premium/race gas. I imagine I'll have to make some slight adjustments to the carb but I don't think the carb will be any more sensitive. For the most part I've rarely had to adjust my jetting on this bike. With the larger bore and port work I'll have to add more fuel I would think. I'll start at the next jet size and probably move the needle clip.

The stage 3 cam is recommended for big bore kits and should compliment the head porting very well. There are some other cam manufacturers such as pro circuit but I couldn't find much for feedback on them. And my buddies 650L will definitely be getting the stage 1.

[Moses Ludel]

Any comparisons around the use of a bronze bushing?  Is there enough small-end shank to allow room for a bushing on the OEM rod, or is the OEM rod considered a waste of time?  You prompted me to view the rods at Wossner's site:  beautiful stuff!  The photo for all of the rod applications is the same, so I can't tell whether your CRF450 uses a press-in bronze bushing (as shown in this pic).  I'm guessing this is Wossner's approach from the website pics:  https://wossnerpistons.com/collections/connecting-rods

A carburetor should be easy to tune, you've dealt with the altitude variations before...Exciting!

 

[53HiHood]

This engine build has been a nightmare. I’m always waiting on parts and now sending parts back due to poor quality control. When I decided on the work I wanted done I wasn't given cam recommendations. I found the hotcams stage 3 but I didn’t feel it would work with my build, especially so after talking with one of their techs. I finally got the shop to give me a recommendation for a custom cam in mid January and by the time the cam was built and shipped it was mid February. I haven’t had the bike out once, It’s currently sitting in the shop with no cylinder head. I had the head CNC ported and when they did the valve job they didn’t check valve recess depth in the seats. When I got the head and installed everything the shims required to get the proper clearance were a couple sizes from the smallest, so not much room to adjust the valves later on. I had to disassemble the entire top end and send the head back. That was almost two weeks ago. I have to hope that they at least send new top end gaskets otherwise I’ll have to order those and continue waiting. I’m going to be looking for a new shop next time I need engine work done.

Here are some shots of the engine...

Starting assembly

The new rod does have a bronze bushing in the small end

A view into one of the intake runners shows metallic particles loosely attached and or broken off. Not a very clean job.

When the custom built Ron Hamp RHC22 camshaft showed up.....

 

I did run the engine for two 10 minute heat cycles at 2000-2200 rpm before having to remove the head to return it for warranty work. My fueling was off and I’ve never had so much trouble starting this bike. Prior to this engine work, the bike never needed more than 3 kicks, even when I was on the mountain. I had the jetting set to stock and just wasn’t getting enough fuel. I kicked for over an hour before giving up the night I finished assembling it. I replaced the stock 42 pilot jet (slow jet) with the only larger size I had which was a 50 and the bike fired up. I since replaced that with a 45 and that’s what I’ll try when I get the head back. I’m told by the shop that I will possibly run leaner jetting because the engine will pull more fuel from the jets than a standard bore engine. Definitely not the case for start up. 

[Moses Ludel]

53HiHood...One simpler approach to recessed valve seats, when practical, is to mill the valve stem ends to increase the free play/clearance.  In your case, this would allow a wider range of shim adjustment.  Did the shop suggest this? 

You would be sending just the valves with your specifications on how much additional clearance you want/need.   (Automotive machine shops can cut valve stems.  This was once a standard procedure for restoring worn tips or compensating for recessed seats and milled head decks.  The issue is clearance and preventing parts interference.)  There is one limitation and concern:  The shortened valve stem end must not create parts interference.  The cam followers/lifters, rocker arm tips and the valve spring retainers must align and not interfere with each other over the full rotation of the camshaft.

Moses

[53HiHood]

The shop did not suggest that. The issue was they took to much material from the seats and should have started with new seats. I got it worked out, not without additional headache. They replaced the seats. I also had them clean up their porting work. I got the bike out on tuesday for a short ride, nothing aggressive. No leaks, weird noises, etc. Bike ran great. I kept jetting at factory settings minus a 45 slow jet. The bike fired on the 3rd or 4th kick after re-assembly. I may get out for a ride tomorrow but that may be it for the year as my schedule is shot after this weekend.

[Moses Ludel]

Understood...Glad the shop stood behind its work.  Yes, seat height is critical, new seats are the fix when much material is involved.

Keep us posted on your hot CRF450 mods when you do get more seat time...

[53HiHood]

We’ll have to revisit this next winter.

[Moses Ludel]

I chose L.A. Sleeve Company for the cylinder head work and iron/moly cylinder sleeve/liner that I did on my Honda XR650R.  I'm pleased with their work.  When you need machining of motorcycle cylinders and heads, contact Nick Metchkoff at L.A. Sleeve.  Let Nick know that I suggested you contact him.  He will be forthright about what they do and can do...He may also have ideas about your outsourcing of other machine work.

http://www.4wdmechanix.com/Rebuilding-the-HondaXR650R-Cylinder-and-Head-at-L.A.-Sleeve-Company?r=1

https://www.lasleeve.com/