Piston Rings

Piston rings

Fitting in a new or rebored cylinder





1. Push the piston rings down into the cylinder one by one, using a piston to position them correctly.
2. Measure the ring gap with a feeler gauge, see illustration. If necessary, the gap can be increased with a special file. For measurement information, see Pistons.

Fitting in a worn cylinder
Piston rings for a worn cylinder should be matched in the same way as for a new or rebored cylinder, but they must be tried at the lower limit of piston travel because the bore is narrowest at this point.

In connection with piston ring replacement, the cylinder bore should be honed before the rings are fitted.





a. Use a piston ring clamp to fit the rings on the piston.

b. The lower compression ring should be fitted with the side marked "top" facing up.





c. Check the fit of the piston rings in their grooves by rolling them round the grooves. Also measure the clearance at several points.

d. Oil the piston and rings before assembly. Turn the compression rings so that their gaps are roughly 180 to each other and position each of them above one of the gudgeon pin holes.

e. Make sure that the gaps in the top and bottom rings of the three-part scraper ring are staggered round the piston and not in line with each other.