Valve Seat Reconditioning - Polaris 2012 RANGER RZR 570 INTL Service Manual

ENGINE / COOLING SYSTEM

Valve Seat Reconditioning

Valve se at reconditioning should be pe rformed by a
technician pr oficient in cylinder hea d reco nditioning
techniques. Reconditioning techniques vary, so follow the
instructions pr ovided by the valve
equipment m anufacturer. D o not grind seats m ore t han
necessary t o provide p roper seat su rface, w idth, and
contact point on valve face.
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, a nd u neven sur face. If a ny of the a bove
conditions exist, the valve seat must be 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, causing carbon
accumulation and possible compression loss. If the seat is
too n arrow, he at tr ansfer fr om va lve to se at is r educed.
The valve may over heat an d warp , r esulting 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:
3.46
reco nditioning
WARNING
9923523 - 2012 RANGER RZR 570 Service Manual
© Copyright 2011 Polaris Sales Inc.
* If the contact area is less than 75% of the circumference
of the seat, r o tate 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 on ly t he a mount o f
necessary to repair the seat surface.
5. To ch eck the con tact area o f the seat on the valve
face, apply a thin coating of Prussian Blue paste to th e
valve seat. If using an interference angle (46°) apply
black permanent marker to the entire valve face (A).
6. Insert valve into guide and tap valve lightly into place
a few times.
7. Remove valve an d check where the Pru ssian Blu e
indicates seat contact o n the valve face . The valve
seat should co ntact th e middle of th e valve face or
slightly above, and must be the proper width.
* If the indicated seat contact is at the top edge of the valve
face and contacts the margin area (B) it is too high on the
valve face. Use the 30° cutter to lower the valve seat.
* If too lo w, use the 60° cu tter to raise th e se at. When
contact area is centered on the valve face, measure seat
width.
* If the seat is too wide or uneven, use both top and bottom
cutters to narrow the seat.
* If the seat is too narrow, widen using the 45° cutter and
re-check contact point on the valve face and seat width
after each cut.
material
A