1997 Ski-Doo Factory Shop Manual Volume Two, Page 76Get this manual
Sub-Section 03
Section 03 ENGINE (454, 494, 583 AND 670 ENGINE TYPES)
' done without removing the engine from chassisCLEANING
Discard all gaskets and O-ringsClean all metal components in non-ferrous metal cleanerScrape off carbon formation from cylinder exhaust port, cylinder head and piston dome using wooden spatulaNOTE: The letters "AUS" (over an arrow on the piston dome) must be visible after cleaningClean the piston ring groove with groove cleaner tool, or with piece of broken ring
NOTE: The following procedures can be
RAVE System
' Variable Exhaust
NOTE: RAVE stands for Rotax Adjustable
Remove spring clip no3, cover no5 and spring no6Cut clamp no8 (remove spring on 454) and unscrew valve piston no7Spread clamp no10 (except 454) and remove bellows no9Remove cylindrical screws no11 and their washers no12 then valve rod housing no13Pull out exhaust valve no16