Polaris 2007 Sportsman 450 EFI, Service Manual

Page: 88 / 406

3.30
ENGINE
2. Measure piston pin O.D. Replace piston and/or piston pin
if out of tolerance.
3.
Measure connecting rod small end ID.
4. 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 at right.
2. Measure installed gap with a feeler gauge at both the top
and bottom of the cylinder.
NOTE: A difference in end gap indicates cylinder taper.
The cylinder should be measured for excessive taper
and out of round
3. If the bottom installed gap measurement exceeds the
service limit, replace the rings. If ring gap is below
specified limit, file ring ends until gap is within specified
range.
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.
Crankcase Disassembly
NOTE: The recoil starter, starter motor, starter drive, flywheel,
stator, cam chain and sprockets can be serviced with the engine
in the frame.
Piston Ring-to-Groove Clearance
Top Ring Std: .0016-.0031” (.040-.080 mm)
Limit: .0059” (15 mm)
Second Ring Std: .0012-.0028” (.030-.070 mm)
Limit: .0059” (15 mm)
Piston
Ring
Feeler Gauge
Piston Ring Installed Gap
Top Ring
Std: .0079- .0138” (.20- .36 mm)
Limit: .039” (1.0 mm)
Second Ring
Std: .0079- .0138” (.20- .36 mm)
Limit: .039” (1.0 mm)
Oil Ring
Std: .0079- .0276” (.20- .70 mm)
Limit: .059” (1.5 mm)
Feeler Gauge
Cylinder
Piston Ring
25-50 mm