2011 Arctic Cat 400 TRV ATV Service Manual, Page 11Get this manual
NOTE: The engine should be warm (operating temperature) and the battery full charged for an accurate compression testThrottle must be in the wide-open throttle (WOT) positionIn the event the engine can not be run, cold values are included CAUTION
Before removing spark plug, be sure to clean the area around the spark plugDirt could enter engine when removing or installing the spark plug
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)PSI Hot (WOT)
95-115 120-140
Adjust the gap to 0.7-0.8 mm (0.028-0.032 in for proper ignitionUse feeler gauge to check the gap
COMPRESSION PSI Cold (WOT)
NA 80-120
6If compression is abnormally low, inspect the following itemsAVerify starter cranks engine over at normal speed (approximately 400 RPM)BGauge functioning properlyCThrottle lever in the full-open positionDValvetappet clearance correctEValve not bent or burnedFValve seat not burnedNOTE: To service valves, see Section 3ATV0052C