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ENGINE
3.9
HONING TO OVERSIZE
CAUTION: If cylinder wear or damage is excessive,
it will be necessary to oversize the cylinder using a
new oversize piston and rings. This may be
accomplished by either boring the cylinder and then
finish honing to the final bore size, or by rough honing
followed by finish honing.
CAUTION: For oversize honing always wet hone
using honing oil and a coarse roughing stone.
Measure the piston (see piston measurement) and
rough hone to the size of the piston. Always leave
.002 - .003″ (.05 - .07 mm) for finish honing. Refer to
piston-to-cylinder clearance specifications on Page
3.4 before honing. Complete the sizing with fine grit
stones to provide the proper cross-hatch finish and
required piston clearance.
EXAMPLE OF CROSS HATCH PATTERN
A finished cylinder should have a cross-hatch pattern
to ensure piston ring seating andto aid in theretention
of the fuel/oil mixture during initial break in. Hone
cylinder according to hone manufacturer’s
instructions, or these guidelines:
S Use a motor speed of approximately
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 (or cylinder centered
on arbor) and to bring the stone
approximately 1/2″ (1.3 cm) beyond the
bore at the end of each stroke.
S Release the hone at regular intervals and
inspect the bore to determine if it has
been cleared, and to check piston fit.
NOTE: Do not allow cylinder to heat up
during honing. The thinner areas of the
liner around the ports will expand causing
uneven bore.
S After honing has been completed inspect
all port opening areas for rough or sharp
edges. Apply a slight chamfer to all ports
to remove sharp edges or burrs, paying
particular attention to the corners of the
intake and exhaust ports.
CLEANING THE CYLINDER
AFTER
HONING
It is very important that the cylinder be thoroughly
cleaned after honing to remove allgrit material. Wash
the cylinder in a solvent, then inhot, 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 2 Cycle
Lubricant.
CRANKSHAFT
STRAIGHTENING
Lubricate the bearings and clamp the crankshaft
securely in the Crankshaft Truing Stand (PN
2870569). Refer to the illustrations below.
Crankshaft Truing Stand
(PN 2870569)
NOTE: The rod pin position in relation to the dial
indicator position tells you what action is required to
straighten the shaft.
A
B
HIGH .004 (.1mm)
HIGH .004 (.1mm)
SUPPORT CRANKSHAFT
HERE.
1. To correct a situation like the one shown in the
illustration at right, strike the shaft at point A with a
brass hammer.