Engine Assembly; Crankcase Preparation - Upper; Piston Ring Installation - Polaris Sportsman 850 Service Manual

ENGINE / COOLING SYSTEM

ENGINE ASSEMBLY

CRANKCASE PREPARATION - UPPER

1. Refer to Oil Flow Diagram (page 5.4, page 3.6) and
trace the oil path through the upper crankcase /
cylinder. Flush all oil passages with solvent and then
warm soapy water. Rinse with clear, warm water and
dry with compressed air. Be sure passages are clean
and dry before assembling the upper crankcase.

PISTON RING INSTALLATION

Apply clean engine oil to rings. Check ring installed gap
before installation. Clean accumulated carbon from ring
grooves and lubrication holes if piston has been in
service.
1. Place oil control ring expander in oil ring groove. Tips
of expander gap (A) must face piston crown so
scraper edge (B) of expander faces piston skirt.
2. Rotate expander in groove until butt ends are on
intake side of piston. Ends must butt squarely
together and must not overlap.
3. Install bottom rail first, then top rail with end gap
located as shown at right.
3.66
4. Install second ring with undercut facing bottom of
piston. Rotate ring to place end gap generally toward
(intake) side of piston as shown below.
5. Install top ring with "0" mark facing up (toward piston
crown) and rotate to position the gap generally at the
front as shown below.
6. Be sure top and second rings rotate freely in their
grooves and do not bind when compressed by hand.