
03-19
SECTION 03 - ENGINE PREPARATION
All Engines
The RAVE valve does not allow an engine to make
higher peak horsepower than an engine not so
equipped, it can however make moving the peak
horsepower higher practical, because of its effect
on the rest of the power curve. Item 2 in the fol-
lowing figure is the power curve of an engine with
the RAVE valve held fully open through its entire
RPM range. Item 6 notes the peak power pro-
duced. That peak will not change if the exhaust
port time of a similar engine without a RAVE valve
was the same (with all other features equal).
Item 1 is the power curve of the engine with the
RAVE valve closed through its entire RPM range.
The shaded area (item 3) is the improvement in
power at lower engine speeds that is gained be-
cause of the lower exhaust port. If the port re-
mains at this height however, the power would
peak as noted in item 5. Raising the exhaust port
at the proper RPM (item 7) will allow the engine
peak power to continue to rise (item 6).
Item P1 in the figure is the force of the return
spring against the diaphragm. The exhaust pres-
sure must be high enough to overcome this force
before the valve begins opening. Item P2 is the
pressure required to completely open the RAVE
valve. Between P1 and P2, the usable power
curve of the engine is moving from curve 1 to
power curve 2. This transition takes place very
rapidly at full throttle and from a practical stand-
point can be considered to be instantaneous at
item 7. Gradual application of the throttle, howev-
er, will result in the RAVE valve opening much later.
If the RAVE valve opens toos late, the engine will
bog or hesitate momentarily as the RPM increas-
es. Full peak performance (item 6) is still available.
From a functional point of view. It is better to have
the valve open a bit early than a bit late.
Rave Valve Adjustment
To adjust the RAVE valve turn the red adjustment
knob all the way in (clockwise). Open the red knob
1 turn out (counterclockwise) and perform an ac-
celeration run on the craft starting from zero and
accelerating to full speed. Repeat the procedure
until you attain the best performance. The use of
a radar gun with acceleration recording capabili-
ties is advised in order to obtain accurate data,
however rider observation will surface.
Maintenance
The RAVE components should be periodically
checked. The RAVE valve requires cleaning of car-
bon deposits. Cleaning intervals would depend
upon the user’s riding style and the quality of the
oil used. Using FORMULA XP-S synthetic injec-
tion oil, clean the valve periodically. Check for
clean passages between the exhaust port and di-
aphragm chamber. If cleaning is necessary, use
solvent to remove the deposits. Also check the
diaphragm for punctures, replace if damaged.
No special solvents or cleaners are required when
cleaning the valve.
P1
P2
7
6
4
5
3
1
1
2
POWER
RPM
A18C02A
Содержание Bombardier
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