Kohler — Measuring Piston-to-Bore Clearance
Testing & diagnosis · piston/cylinder
From a Kohler service manual covering: CH18, CH20, CH22, CH23, CH25, CH620, CH630, CH640, CH670, CH680, CH730, CH740…. Check it applies to your exact model before use.
Applies to: Kohler CH18, Kohler CH740
Before you start
- Do not use a feeler gauge to measure piston-to-bore clearance.
Procedure
- Use a micrometer and measure diameter of piston 6 mm (0.24 in.) above bottom of piston skirt and perpendicular to piston pin.
- Use an inside micrometer, telescoping gauge, or bore gauge and measure cylinder bore approximately 63.5 mm (2.5 in.) below top of bore and perpendicular to piston pin.
- Piston-to-bore clearance is difference between bore diameter and piston diameter.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 6 mm (0.24 in.)
- 63.5 mm (2.5 in.)
Full service-parts list: Kohler CH740 →
Source: Kohler service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.