Combustion Chamber Cleaning; Valve Seat Reconditioning - Polaris RANGER 500 2018 Service Manual

COMBUSTION CHAMBER CLEANING

CAUTION
Wear eye protection during combustion chamber
cleaning.
1. Clean all accumulated
combustion chambers and valve seat area
CAUTION
Carbon Clean Fuel Treatment (2871326) can be used
to help remove carbon deposits.
Do not use a metal scraper, a coarse wire brush or
abrasive cleaners to clean the cylinder head. Damage
may result.
2. Visually inspect cylinder head gasket surface and
combustion chamber for cracks or damage. Pay
close attention to the areas around spark plug and
valve seats.

VALVE SEAT RECONDITIONING

Valve seat reconditioning should be performed by a
technician proficient in cylinder head reconditioning
techniques. Reconditioning techniques vary, so follow
the instructions provided by the valve reconditioning
equipment manufacturer. Do not grind seats more than
necessary to provide proper seat surface, width, and
contact point on valve face.
CAUTION
Wear eye protection or a face shield during cylinder
head disassembly and reassembly.
Valve Seat Inspection
Inspect valve seat in cylinder head for pitting, burnt
spots, roughness, and uneven surface. If any of the
above conditions exist, the valve seat must be
9928485 R01 - 2017-2018 RANGER 500 / 570 Service Manual
© Copyright Polaris Industries Inc.
reconditioned. If the valve seat is cracked the cylinder
head must be replaced.
Valve seat width and point of contact on the valve face is
very important for proper sealing. The valve must contact
the valve seat over the entire circumference of the seat,
and the seat must be the proper width all the way
around. If the seat is uneven, compression leakage will
result. If the seat is too wide, seat pressure is reduced,
carbon deposits from
causing carbon accumulation and possible compression
q
.
loss. If the seat is too narrow, heat transfer from valve to
seat is reduced. The valve may overheat and warp,
resulting in burnt valves.
Renewing Valve Seats
1. Install pilot into valve guide.
2. Apply cutting oil to valve seat and cutter.
3. Place 46° cutter on the pilot and make a light cut.
4. Inspect the cut area of the seat:
ENGINE / COOLING SYSTEM
* If the contact area is less than 75% of the
circumference of the seat, rotate the pilot 180° and
make another light cut.
* If the cutter now contacts the uncut portion of the
seat, check the pilot. Look for burrs, nicks, or runout.
If the pilot is bent it must be replaced.
* If the contact area of the cutter is in the same place,
the valve guide is distorted from improper installation.
* If the contact area of the initial cut is greater than
75%, continue to cut the seat until all pits are
removed and a new seat surface is evident.
NOTE
Remove only the amount of material necessary to
repair the seat surface.
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