2004 Ski-Doo REV Series Factory Service Manual, Page 145Get this manual
Section 04 ENGINE Subsection 02 (ENGINE LEAK TEST AND DIMENSION MEASUREMENT)
RINGPISTON GROOVE CLEARANCE
Using feeler gauge check clearance between rectangular ring and grooveReplace piston if clearance exceeds specified toleranceRefer to TECHNICAL DATA
Measuring (in crankcase) First, check deflection with crankshaft in crankcaseIf deflection exceeds the specified tolerance, recheck deflection using V-shaped blocks to determine the defective part(s)See belowMeasuring (on bench) Once engine is disassembled, check crankshaft deflection on V-shaped blocksIf deflection exceeds the specified tolerance, it can be worn bearings or bent crankshaftRemove crankshaft bearings and check deflection again on V-shaped blocks to determine the defective part(s)See measurement in following illustration