2002 Bombardier Quest 650XT Service Manual, Page 46Get this manual
Section 03 ENGINE Subsection 02 (TROUBLESHOOTING)
CYLINDER AND HEAD
SYMPTOM CONDITION TestInspection UNUSUAL ENGINE NOISE ANDOR VIBRATIONNORMAL USE1Check noise coming from cylinder head areaaFaulty chain tensionerReplace spring andor mechanismbChain guide worn outReplace chain guidecStretched chain andor worn out sprocketsReplace chain and sprocketsdSprocket screws got looseRetighten screws with recommended torqueeHydraulic element inside rocker arm(s) is(are) worn out (valve adjustment)Replace rocker arm(s)fRocker arm screws not tightenedReplace screws and perform the torque procedure (refer to CYLINDER AND HEAD)SYMPTOM CONDITION TestInspection OIL CONTAMINATION ON CYLINDER ANDOR HEADNORMAL USE1Check screws for torqueaLoose screwsRetighten screws with recommended torquebGaskets are brittle, hard, worn out or otherwise damagedReplace damaged gaskets, O-rings or the V-ring on breathercSpark plug in the contact area to ignition coil fouled by oilClean spark plug area and replace spark plug tube