Yamaha XZ550RJ 1982 Service Manual page 60

2. Piston ring/ring groove fit must have correct
clearance. If the piston and ring have already
been used in the engine, the ring must be re-
moved, the ring groove cleaned of carbon,
then the ring should be reinstalled. Use a
feeler gauge to measure the gap between the
ring and the land.
Piston ring
The oversize top and middle ring sizes are
stamped on top of the ring.
The expander spacer of the bottom ring (oil control
ring) is color-coded to identify sizes. The color mark
is painted on the expander spacer.
1. Measure the end gap of each piston ring.
Insert a ring into the cylinder, and push it
approximately 20mm (0.8 in) into the cyl-
inder. Push the ring with the piston crown
so the ring will be at a right angle to the cyl-
inder bore.
2. Measure the ring end gap with a feeler
gauge. If the end gap exceeds tolerance,
replace the whole set of rings.
NOTE:
You cannot measure the end gap on the expander
spacer of the oil control ring. If the oil-control-ring
rails show excessive gap, replace all three rings.
60