Bombardier SeaDoo 2001 factory shop manual, Page 106Get this manual
Section 04 ENGINE Subsection 05 (TOP END)
GENERAL
The 2-stroke ROTAX engine rotates counterclockwise seen from the rear (PTO flywheel)The 717 and 787 RFI engines have rotary valve to control opening and closing of the intakeThe 947 engine uses reed valves in the crankcaseThe 787 RFI and 947 engines are also equipped with the RAVE system (Rotax Adjustable Variable Exhaust)CAUTION: No engine components can be interchanged between engines
RAVE System (Rotax Adjustable Variable Exhaust)
BASIC OPERATION The RAVE valves change the height of the exhaust portThe RAVE valve solenoid, which is controlled by the MPEM, allows either positive crankcase pressure (787 RFI and 947 with carburetor) or pressure from the air compressor (947 DI) to inflate the bellows and open the RAVE valvesCarburetor-Equipped Engines On top of the RAVE, there is red plastic adjustment knobTurning the adjustment in or out changes the preload on the return spring which, in turn, will change the RPM at which the RAVE valve opens and closesOn 947 engines, the spring preload does not have significant effect on the valve operation787 RFI and 947 Carburetor-Equipped Engines On these engines, the RAVE valves are controlled by the Multi-Purpose Electronic Module (MPEM)To open the RAVE valves, the MPEM activates solenoid which directs the positive pressure from engine crankcase to the valves