Pistons, Rings & Pins

1. Inspect outer circumferences of all pistons for seizure or scoring, replacing as necessary.
2. Measure outer diameter of each piston at right angle to piston pin, .87 inch (22mm) below oil ring land lower edge. Piston diameter should be 3.5411-3.5419 inches (89.944-89.964mm). Pistons are available in .01 and .02 inch (.25 and .5mm) oversize.
3. Check piston to cylinder clearance. On 1989-91 models measurement should be between .0019-.0026 inch (.049-.065mm).On 1992 models measurement should be between 0.0009-0.002 inch. If clearance exceeds .0059 inch (.15mm), replace piston or rebore cylinders to fit oversize pistons. Whenever replacing pistons, use new piston rings.
4. Measure piston ring to ring land clearance around entire circumference with new piston ring. Clearance should be .0012-.0028 inch (.03-.07mm). If clearance exceeds .006 inch (.15mm), replace piston.
5. Inspect piston rings for damage, abnormal wear or breakage, replacing as necessary.
6. Insert piston ring into cylinder by hand and use piston to push it to bottom of ring travel.
7. Measure each piston ring end gap. If end gap exceeds .039 inch (1mm), replace ring(s).
8. Measure piston pin hole diameter, which should be .905-.9055 inch (22.988-23mm).
9. Measure piston pin diameter, which should be .9045-.9047 inch (22.974-22.980mm).
10. Check piston pin to piston clearance. If clearance is not .0003-.0010 inch (.008-.026mm), replace piston and/or pin.