2003 Arctic Cat ATVs from 250cc to 500cc Service Manual, Page 215Get this manual
2Acceptable 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
1Apply grease to the inside surface of the valve seals; then place lower spring seat and valve guide seal over each valve guide
PISTON ASSEMBLY
NOTE: Whenever piston, rings, or pin are out of tolerance, they must be replaced
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 oil2Insert each valve into its original valve location3Install the valve springs with the painted end of the spring facing away from the cylinder head NOTE: If the painted end is not visible, install the ends of the springs with the closest coils toward the head