Service Manual

5.50
ENGINE
6. Measure in two directions (front to back and side to side)
on three levels and record measurements. If cylinder is
tapered or out of round beyond .001", the crankcase must
be replaced.
Piston-to-Cylinder Clearance
Measure piston outside diameter at a point 33 mm down from
piston crown, at a right angle to piston pin bore.
Subtract measurement from maximum measurement obtained
in Step 6 of Cylinder Inspection.
Honing - Important Information
The NiCaSil cylinders have a cross-hatch pattern of
approximately 45 degrees to ensure piston ring seating, reduce
ring vibration, and to aid in lubrication retention. The factory
applied crosshatch is good for the service life of the cylinder and
honing IS NOT required when installing new pistons and / or
piston rings.
DO NOT attempt to hone the NiCaSil cylinders. A special
process is required, and improper honing or use of the wrong
type of abrasive stone will result in irreversible cylinder wall
damage.
Any change in surface finish should be followed by cylinder
measurement and an inspection for wear. If cylinders are
damaged or worn beyond the service limit, they can be re-plated
with NiCaSil one time only
by a NiCaSil plating specialist.
If cylinder damage is excessive, or if cylinders have been
replated before, it will be necessary to replace the cylinder /
crankcase assembly.
= In. / mm.
Cylinder Taper Limit:
.001" (.025mm) Maximum
Cylinder Out of Round:
Limit: .001" (.025 mm) Maximum
Standard Bore Size
3.4252" ± .0005 (87 mm ± .01mm)
1/2” Up From Bottom
1/2” Down From Top
Piston to Cylinder Clearance:
.0021" ± .0013" (.053mm ± .03mm)
Piston O.D. (Standard):
3.4231" ± .0008" (86.947 ± .02 mm)
(33.0 mm)
1.30 in.