2010 Arctic Cat DVX 90 / 90 Utility ATV Service Manual, Page 26Get this manual
CAUTION If valves are discolored or pitted or if the seating surface is worn, the valve must be replacedDo not attempt to grind the valves or severe engine damage may occur
Measuring Rocker Arm to Shaft Clearance 1Using dial calipers, measure the inside diameter of the rocker arm2Using micrometer, measure the outside diameter of the rocker arm shaft3Subtract the shaft diameter from the rocker arm diameter4Acceptable clearance must be within specificationsInstalling Valves 1Apply grease to the inside surface of the valve seals; then place valve guide seal over each valve guideYT138
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 top of the piston2Inspect the piston for cracks in the piston pin, boss, top, and skirt areas3Inspect the piston for seizure marks or scuffingIf piston is scored or galled, replace it with new one4Inspect the perimeter of each piston for signs of "blowby" indicated by dark discoloration"Blowby" is caused by worn piston rings, excessive carbon in ring grooves, or an out-of-round cylinderRemoving Piston Rings 1Starting with the top ring, slide one end of the ring out of the ring-groove