2004 Ski-Doo Racing Handbook, Page 66Get this manual
SECTION 04ENGINE PREPARATION
Operation
The RAVE valve does not allow an engine to make higher peak horsepower than an engine not so equipped, it can make moving the peak higher practical because of its effect on the rest of the power curveItem in following illustration is the power curve of an engine with the RAVE valve held fully open through its entire RPM rangeItem notes the peak power producedThat peak will not change if the exhaust port time of similar engine without RAVE valve was the same (with all other features equal)P1 P2 6
If the RAVE valve opens too late, the engine will bog or hesitate momentarily as the RPM increasesFull peak performance (item 6) is still availableFrom functional point of viewit is better to have the valve open bit early than bit lateThis fact is due to certain dynamic conditions that exist on the snowmobile, i.e the clutch and torque converter
Adjustment
The red cap on the RAVE valve cover should be turned all the way in and bottomed in normal useBacking the red adjuster out will reduce the spring preload and allow the RAVE valve to open at lower RPMAt high altitudes, exhaust gas pressures will drop and the spring preload may have to be decreasedIt is doubtful that any adjustment will be required up to an altitude of 2400 (8000 ft)Above that, however, the spring preload can be reduced by turning the red adjustment screw out up to maximum of four turnsThe only other time adjustment of the spring preload should be considered is if the engine has been modified in any wayAVAILABLE RAVE SPRINGS