Yamaha MM700A, Manual, Page: 114 / 282

108 CHAPTER FOUR
Measure the end gap with a flat feeler gauge (Fig-
ure 33, typical) and compare to the specified gap in
Table 2 or Table 3.
If the gap is greater than specified, replace the rings
as a set.
NOTE
When installing new rings, measure the end
gap as
in Step 6. I f the gap is less
than specified, make sure they are the cor-
rect piston rings. I f the replacement rings
are correct the end gap is too small,
carefully file the ends (Figure 34) with a
fine cut file until the gap is correct.
gap allows the ends to together
and the ring, which may cause exces-
sive piston and cylinder damage.
CAUTION
An old ring can be broken and used to clean
carbon from the ring groove as shown in
Figure 35.
Be careful to remove only
the grooves and do not cut into the
soft aluminum of the piston. Some rings and
their grooves have the top tapered, so be
careful when cleaning the grooves. I f the
grooves are damaged while cleaning, install
a
new piston.
7. Carefully remove all carbon buildup from the ring
grooves. Inspect the piston for missing, broken or cracked
ring lands. Inspect the grooves carefully for cleanliness
and for absence of burrs or nicks. Recondition or replace
the piston
if necessary.
8. Check the side clearance of ring as follows:
a. Install the piston rings as described under Piston In-
Using a feeler gauge, measure the piston ring side
clearance (Figure 36). Compare the measurement
with the specified side clearance in Table 2 or Table
3. If the side clearance is greater than specified, in-
stall a new piston ring and recheck the side clear-
ance. If the side clearance remains excessive,
replace the piston.
9. Inspect the condition of the piston crown. Remove nor-
mal carbon buildup with a wire
or scraper. If the pis-
ton shows signs of overheating, pitting or other abnormal