Engine Cylinder Hones and Glaze Busters

[Moses Ludel]

There are many times when a light engine rebuild is possible.  If cylinder taper (wear toward the top of the piston ring travel and TDC) is negligible and the cylinder is still "round" in bore shape, honing can restore the cylinder(s) to get a good piston ring seal on new rings.  This is the traditional "ring and valve job" overhaul procedure, where the piston(s) are reusable and the rings will be renewed after cleaning the ring grooves carefully with the correct tool.

 

This is a precisely honed motorcycle cylinder from the magazine's Honda XR650R.  L.A. Sleeve has achieved this true, perfect cross-hatch with the use of a power cylinder hone.  Machine shops strive for this type of cross-hatch pattern. For more details, see the magazine's how-to HD video series on the top end rebuild of the XR650R engine.

 

Whether to "hone" or "glaze bust" is a matter of wear and how true the cylinder measures.  A three- or four-stone cylinder hone is capable of truing the bore and also creating a "cross-hatch" pattern desirable for good ring seating and seal.  The cross-hatch is actually done precisely on a boring/honing machine when an engine or cylinder barrel gets reconditioned at a machine shop.  When performed at the machine shop environment, actual angle or "degrees" of the cross-hatch intersect lines achieve a precise angle.  This is controlled by the speed of the hone going up and down in the cylinder.

 

 

At left is a flex hone or "glaze buster" with silicone balls mounted on stiff wire strands. Note that the hone must match the bore diameter of the cylinder being serviced.  At center is a three-stone hone, known for better control of cylinder "round" and best for truing a cylinder.  The stone package at right is "240 Grit", there are other grits for different honing finishes and speeds.

 

If you choose to hone your cylinder and not sublet it to a machine shop, there are two distinct procedures: 1) honing with a stone hone and 2) breaking the glaze with a silicone ball glaze buster or "flex hone". 

 

Again, for precisely truing, the stone hone will be best.  The silicone flex hone is a brush-like approach with pressure at each wire/ball.  The glaze buster will follow the contour of a cylinder, and unless round and true, the result will be a glaze bust with cross-hatch that mimics the bore's shape.

 

So, the best start is to measure the bore accurately for taper, out-of-round and size.  If you can hone without making the cylinder oversized, the new rings and piston-to-wall gap will be within tolerance.  Follow the manufacturer's recommendations for bore size, piston-to-wall clearance and the piston ring end gaps.

 

Some like the flex hone for its ease of operation and relatively failsafe results.  The stone hone, by contrast, must be used with caution and safely.  There is the chance of breaking the stones or damaging the bore if you do not use the stone hone properly. 

 

See the forum on "General Repairs and Technical Tips" for details on the actual use of cylinder hones... 

 

Moses

 

 

[forman]

Thanks Moses, I just need to jump in and do this.  Having never seen the process I'm anxious about the work required to do it right.

[Moses Ludel]

Read my reply at the General Repairs and Technical Tips topic: http://forums.4wdmechanix.com/topic/295-how-to-hone-an-engine-cylinder/.  Also, take some "Forman" photos and accurate measurements of the cylinder you plan to hone.  Share these details at the "How to Hone an Engine Cylinder" topic.  I'll provide further tips based on your findings and photos.

 

You can do this, Forman!

 

Moses