2001 Arctic Cat ATVs factory service and repair manual, Page 31Get this manual
5While holding the throttle lever in the full-open position, crank the engine over with the electric starter until the gauge shows peak reading (five to 10 compression strokes)NOTE: For the 250300 cc, the compression should be within range of 157.5-192.5 psi in the full-open throttle positionFor the 400500 cc, the compression should be within range of 63-77 psi in the full-open throttle position ! CAUTION
Before removing the spark plug, be sure to clean the area around the spark plugDirt could enter engine when removing or installing the spark plug
6If compression is abnormally low, inspect the following itemsABCDEFVerify starter cranks engine overGauge is functioning properlyThrottle lever in the full-open positionValvetappet clearance correctValve bent or burnedValve seat burned
Adjust the gap to 0.60.7 mm (0.0240.028 in on the 250300 cc or to 0.70.8 mm (0.0280.032 in on the 400500 cc for proper ignitionUse feeler gauge to check the gapFig2-48
NOTE: To service valves, see Section 3
7Pour 29.5 ml (1 fl oz) of oil into the spark plug hole, reattach the gauge, and retest compression8If compression is now evident, service the piston rings (see Section 3)ATV0052B