3.46
ENGINE / COOLING SYSTEM
9923523 - 2012 RANGER RZR 570 Service Manual
© Copyright 2011 Polaris Sales Inc.
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 reco nditioning
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.
Valve Seat Inspection
Inspect valve seat in cylinder head for pitting, burnt spots,
r
oughness, 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
ver
y 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 narrow, heat transfer from valve to seat 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:
* 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,
ch
eck 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%,
c
ontinue 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 material
nec
essary to repair the seat surface.
5. To check the con tact area of the seat on the valve
fa
ce, apply a thin coating of Prussian Blue paste to the
valve seat. If using an interference angle (46°) apply
black p
ermanent marker to the entire valve face (A).
6. Insert valve into guide and tap v
alve lightly into place
a few times.
7. Remove valve an d check where the Pru ssian Blu e
indicate
s seat contact o n the valve face . The valve
seat should contact the 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
co
ntact area is centered on the valve face, measure seat
width.
* If the seat is too wide or uneven, use both top and bottom
cu
tters 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.
Wear eye protection or a face shield during
cylinder head disassembly and reassembly.
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