Aeon 350cc, Service Manual

Page: 72 / 192

ENGINE
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6. Measure piston ring to groove clearance by placing the
ring in the ring land and measuring with a thickness gauge.
Replace piston and rings if ring-to-groove clearance exceeds
service limits.
PISTON RING INSTALLED GAP
1. Place each piston ring inside cylinder using piston to push
ring squarely into place as shown.
Piston Ring Installed Gap
Top Ring
Std: 0.1-0.3 mm
Limit: 0.8 mm
Second Ring
Std: 0.35-0.5
mm
Limit: 1.0 mm
Oil Ring
Std: 0.2-0.7 mm
Limit: 1.5 mm
2. Measure the gap with a feeler gauge at both the top and
bottom of the cylinder.
NOTE: Measure at two points in the cylinder
A difference in end gap indicates cylinder taper.
The cylinder should be measured for excessive taper and out
of round.
3. If the installed gap measurement exceeds the limit, replace
the rings. If using new rings and the measurement is too
small, file the ring ends to achieve the proper gap.
NOTE: Always check piston ring installed gap after
re-boring a cylinder or when installing new rings. A
re-bored cylinder should always be scrubbed
thoroughly with hot soapy water, rinsed, and dried
completely. Wipe cylinder bore with an oil rag
immediately to remove residue and prevent rust.