Service Manual

58
Disassembly/Inspection and Service
KohlerEngines.com 66 690 01 Rev. C
Measuring Piston-to-Bore Clearance
Piston Detail
A
B
Style A
Style B
Model Dimension A Dimension B
LH630/LH640 6 mm (0.2362 in.) --
LH685/LH690 6 mm (0.2362 in.) 13 mm (0.5118 in.)
LH750/LH755 6 mm (0.2362 in.) 6 mm (0.2362 in.)
NOTE: Do not use a feeler gauge to measure piston-to-
bore clearance–it will yield inaccurate
measurements. Always use a micrometer.
Before installing piston into cylinder bore, it is necessary
that clearance be accurately checked. This step is
often overlooked, and if clearances are not within
specifi cations, engine failure will usually result.
Use following procedure to accurately measure piston-
to-bore clearance:
1. Use a micrometer and measure diameter of piston
above bottom of piston skirt and perpendicular to
piston pin.
2. Use an inside micrometer, telescoping gauge, or
bore gauge and measure cylinder bore. Take
measurement approximately 63.5 mm (2.5 in.) below
top of bore and perpendicular to piston pin.
3. Piston-to-bore clearance is difference between bore
diameter and piston diameter (step 2 minus step 1).