It is important to take your Cylinder Compression as soon as you obtain your bike and, at least, on an annual basis thereafter. This is a great reference value to determine if the pistons, rings, cams, lifters, pushrods and valves are all functioning correctly together. Over time, these parts wear and your cylinder compression will reflect when these items should be checked, adjusted or replaced.

New compression readings should be taken whenever any type of headwork, valve reseating, new head gaskets, etc., is performed in order to evaluate the operational functioning and to have a new reference point for the future.

Final cylinder bore sizes after honing. ¹⁾

* All bore sizes +0.0002 in

• When cylinder requires boring beyond 0.040 in 883cc or 1100cc or beyond 0.30 in 1200 cylinders, the oversize limit has been exceeded and the cylinder must be replaced.
• Boring and honing must be done with gaskets and torque plate in place. Bore the cylinder to 0.003 in under the desired finished size. Hone the cylinder to match the piston clearance using a 280 grit rigid hone followed by a 240 grit ball hone. Hone from the bottom end (crankcase side) of cylinders working for 60 degree cross hatch pattern.

Cylinder Bore Service Limits

- Like this:

• Put in 5th gear
• Lift rear wheel
• Remove spark plugs
• Place a long plastic straw in the spark plug hole
• Rotate tire to move cylinder to bottom dead center - lowest straw position
• Check cylinder diagonal dimension from far bottom of cylinder to lip of spark plug hole
• 883=5.5“
• 1200=5.875

The plastic straw is unable to damage the cylinder and unlikely to fall into the cavity…