2004 Ski-Doo Elite Factory Service Manual, Page 60Get this manual
Section 03 TROUBLESHOOTING Subsection 01 (ENGINE)
ENGINE GENERAL
SYMPTOM ENGINE BACKFIRES
CONDITION
TESTINSPECTION
NORMAL USE1Check spark plugaCarbon accumulation caused by defective spark plugClean carbon accumulation and replace spark plug2Check leakage on intake manifoldaAir leak on intake systemRetighten screws andor replace intake manifold gasket3Check exhaust air leakingaExhaust gasket is leakingRetighten screws andor replace exhaust gasket4Check intake valve(s) for leakingaIntake valve(s) is(are) leakingRepair or replace valve(s)5Check if fuel supply is sufficient at high RPMaFuel line is contaminated andor bent (engine gets lean)Clean andor replace defective part(s)6Check fault codes in B.U.D.SsystemaCheck if electrical actuator(s) isare defectiveReplace defective part(s) (refer to COMPONENT INSPECTION AND ADJUSTMENT)