Inspection
1. Clean the sludge and carbon from the following parts:^ The piston
^ The piston pin
^ The connecting rod
WARNING: Bodily injury may occur if the carburetor cleaning fluid is exposed to the skin or If the fumes are inhaled.
NOTE: It is essential that the piston ring grooves are cleaned of carbon to the bare metal.
2. Clean the varnish from the piston pin by soaking it in carburetor cleaning solution.
CAUTION: Do not scrape the piston skirt.
3. Inspect the piston for the following conditions:
^ Scoring of the skirt
^ Cracks
^ Broken ring groove lands
^ Wear
CAUTION: When fitting pistons, both the piston and the cylinder bore condition must be considered together. Production and service pistons have the same nominal weight and can be intermixed without affecting engine balance. If necessary, used pistons may be fitted selectively to any cylinder of the engine, providing they are in good condition and the same weight. Do not cut oversize pistons down or engine balance will be affected. Finish hone when selecting the piston.
4. Measure the piston diameter. When measuring piston for size or taper, measurement must be made as shown with the piston pin removed. If worn or damaged, replace with a standard or oversize piston.
5. Measure the cylinder bore, with a telescoping gauge. If worn beyond specifications, rebore and hone to size.
6. Subtract the piston diameter from the cylinder bore diameter in order to determine the piston-to-bore clearance.
7. Compare the piston-to-bore clearance with specifications in order to determine if the clearance is in acceptable range.
8. If a used piston is not acceptable, check the service piston sizes and determine if a new piston can be selected. Service pistons are available in standard, and several oversizes.
9. If the cylinder bore must be reconditioned, measure the new piston diameter then hone the cylinder bore to the correct clearance.
10. Select the new piston and mark the piston in order to identify the cylinder for which it was fitted.
CAUTION: Do not reuse piston rings. Fit rings in order to match the cylinder they will be used in.
11. Place the piston into the cylinder at the bottom of the ring travel.