Sea-doo 2001 GS, Shop Manual

Page: 91 / 456

Section 04 ENGINE
Subsection 05 (TOP END)
04-05-4
SMR2000-010_04_05A.FM
GENERAL
The 2-stroke ROTAX engine rotates counterclock-
wise seen from the rear (PTO flywheel).
The 717 and 787 RFI engines have a rotary valve
to control opening and closing of the intake. The
947 engine uses reed valves in the crankcase.
The 787 RFI and 947 engines are also equipped
with the RAVE system (Rotax Adjustable Variable
Exhaust).
CAUTION: No engine components can be inter-
changed between engines.
787 RFI and 947 Engines
These engines are canted at a 30 degree angle
(they are not canted on the same side), lowering
the center of gravity of the watercraft. Cylinder ex-
haust ports are located on the same side of the
intake, allowing a high volume tuned pipe design.
RAVE System
(Rotax Adjustable Variable Exhaust)
BASIC OPERATION
The RAVE system automatically changes the ex-
haust port height based on pressure in the exhaust
system. On 787 RFI and 947 engines, the exhaust
port height is controlled by the MPEM according
to the engine RPM.
On top of the RAVE, there is a red plastic adjust-
ment knob. Turning 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 closes.
787 RFI and 947 Engines
On these engines, the RAVE valves are controlled
by the Multi-Purpose Electronic Module (MPEM).
To open the RAVE valves, the MPEM activates a
solenoid which directs the positive pressure from
engine crankcase to the valves.
1. Solenoid
2. Pressure hose from crankcase
3. To atmospheric pressure
NOTE: A check valve on the pressure line elimi-
nates the negative pressure from the crankcase.
To close the RAVE valves, the MPEM deactivates
the solenoid which blocks the crankcase positive
pressure. The RAVE valves are opened to the at-
mosphere.
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F06D3BA
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