2003 Arctic Cat ATVs from 250cc to 500cc Service Manual, Page 145Get this manual
Measuring Rocker Arm (Inside Diameter)
4Place spring retainer over the valve springs; then using the valve spring compressor, compress the valve springs and install the valve cotters
1Using dial calipers, measure the inside diameter of the rocker arm2Acceptable inside diameter range is 12.000-12.018 mm (0.472-0.473 inMeasuring Rocker Arm Shaft (Outside Diameter)
1Using micrometer, measure the outside diameter
of the rocker arm shaft2Acceptable
outside diameter range 11.973-11.984 mm (0.4714-0.4718 in
Installing Valves
PISTON ASSEMBLY
NOTE: Whenever piston, rings, or pin are out of tolerance, they must be replaced
1Apply grease to the inside surface of the valve seals; then place lower spring seat and valve guide seal over each valve guide
CleaningInspecting Piston
1Using non-metallic carbon removal tool, remove any carbon buildup from the dome of the piston2Inspect the piston for cracks in the piston pin, dome, and skirt areas3Inspect the piston for seizure marks or scuffingRepair with #400 grit wet-or-dry sandpaper and water or honing oil