Page 174 - Manual Oficina Polaris Sportsman 570 2014 a 2016

ENGINE / COOLING SYSTEM

VALVE SEAT RECONDITIONING Renewing Valve Seats
Valve seat reconditioning should be performed by a 1. Install pilot into valve guide.
technician proficient in cylinder head reconditioning
techniques. Reconditioning techniques vary, so follow 2. Apply cutting oil to valve seat and cutter.
the instructions provided by the valve reconditioning 3. Place 46° cutter on the pilot and make a light cut.
equipment manufacturer. Do not grind seats more than
necessary to provide proper seat surface, width, and 4. Inspect the cut area of the seat:
contact point on valve face. * If the contact area is less than 75% of the
circumference of the seat, rotate the pilot 180° and
CAUTION make another light cut.
Wear eye protection or a face shield during cylinder * If the cutter now contacts the uncut portion of the
head disassembly and reassembly. 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,
Valve Seat Inspection
the valve guide is distorted from improper
Inspect valve seat in cylinder head for pitting, burnt installation.
spots, roughness, and uneven surface. If any of the * If the contact area of the initial cut is greater than
above conditions exist, the valve seat must be 75%, continue to cut the seat until all pits are
reconditioned. If the valve seat is cracked the cylinder removed and a new seat surface is evident.
head must be replaced.
Valve seat width and point of contact on the valve face is NOTE
very important for proper sealing. The valve must contact Remove only the amount of material necessary to
the valve seat over the entire circumference of the seat, repair the seat surface.
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, 5. To check the contact area of the seat on the valve
causing carbon accumulation and possible compression face, apply a thin coating of Prussian Blue paste to
loss. If the seat is too narrow, heat transfer from valve to the valve seat. If using an interference angle (46°)
seat is reduced. The valve may overheat and warp, apply black permanent marker to the entire valve
resulting in burnt valves. face (A).

6. Insert valve into guide and tap valve lightly into place
a few times.

3.52 9926803 R06 - 2014-2016 Sportsman 325 / ETX / 450 HO / 570 Service Manual
© Copyright Polaris Industries Inc.