Polaris 850 PRO-RMK 155 2.6" QD 2021, Manual

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9850060 R02 - 2020-2021 850 AXYS™ Long Track Snowmobile Service Manual
© Copyright Polaris Inc.
3.77
CYLINDER HONING
The cylinder bore must be de-glazed whenever new pis-
ton rings are installed. A light honing with fine stones re-
moves only a very small amount of material. A proper
crosshatch pattern is important to provide a surface that
will hold oil, and allow the rings to seat properly. If the
crosshatch is too steep, oil retention will be reduced. A
crosshatch angle that is too shallow will cause ring vibra-
tion, poor sealing, and an overheating of the rings due to
blow-by and reduced contact with the cylinder wall. Serv-
ice life of the pistons and rings will be greatly reduced.
NOTICE
A Nicasil cylinder can be lightly honed with a 320 grit
stone hone but cannot be oversized.
Honing Tools
• Ammco 3950 Hone Kit - SPX PN 2870303 /
commercially available
• Ammco 3956 Honing Stones (320 grit / Oversize)
• Honing Oil - Commercially Available
1. Wash the cylinder with cleaning solvent.
2. Clamp the cylinder in a soft jawed vise by the cylinder
studs.
3. Place hone in cylinder and tighten stone adjusting
knob until stone contacts the cylinder walls (DO NOT
OVERTIGHTEN).
4. Apply honing oil to the stones and cylinder walls. Wet
honing removes more material faster and leaves a
more distinct pattern in the bore.
5. Using a 1/2 in (13 mm) drill motor rotating at a speed
of 300-500 RPM, run the hone in and out of the
cylinder rapidly until cutting tension decreases.
Remember to keep the hone drive shaft centered to
prevent edge loading and always bring the stone
approximately 1/2 in (1.2 cm) beyond the bore at the
end of each stroke.
6. Release the hone at regular intervals to inspect bore
size and finish.
NOTICE
q
is an example of the ideal 135º cross hatch pattern.
7. It is very important to thoroughly clean the
cylinder after honing to remove all grit material.
Wash the cylinder in a solvent, then in hot soapy
water. Pay close attention to areas where the cylinder
sleeve meets the aluminum casting (transfer port
area). Use electrical contact cleaner if necessary to
clean these areas. Rinse thoroughly, dry with
compressed air, and oil the bore immediately with
Polaris Premium 2 Cycle Lubricant.
NOTICE
Always check the piston to cylinder clearance and
piston ring installed gap after honing is complete.
ENGINE / COOLING / EXHAUST