Are RAVE valves really necessary?

[Jim Dawson]

While trying to find the problem why my 97 Challenger has trouble coming off idle after it warms up I first rebuilt the RAVE valves and then totally removed them and covered the hole with a plate and gasket. Guess what, the boat revs almost 1000 rpm faster with the RAVE valves removed than with rebuilt valves (and I had a dealer check the valves after I rebuilt them - the dealer also rebuilt the carbs and replaced the impeller). It doesn't have quite as much low end power without the RAVE valves but its a jet so it goes forward by blowing water out the back, not by screwing it's way through the water -right? I still have a problem with coming off idle when it's warm (it might take 30 seconds to plane) but I don't think it's a RAVE issue since it does OK when it's cold.

What's the infatuation with RAVE valves? I'll take top end. Do I risk any damage?

Also, there's a RAVE looking valve controlling water into the waterbox. Can anyone tell me what that's all about and could that be the problem why the boat has problems reving after it's been running for a while. Should I try cutting off the water to the water box or will I burn something up? I'm thinking that too much water in the exhaust might be keeping the engine from reving.

 

[kustomkarl]

I haven't heard of problems removing the RAVE valves... I'll look into that. It could be a temperature thing at low rpm's. The exhaust needs water to keep from burning up. It doesn't influence the rpm's with water. The "Water Flow Regulator" is an important item needed to distribute the water to the engine and muffler at the exact rpm needed. If you adjust it you will damage the engine.The water flow regulator has been calibrated at the factory and should not be tampered with or modified in any way.
CAUTION: Strictly adhere to the calibration procedure or otherwise serious engine damage will occur.
If engine does not maintain RPM or the engine is experiencing poor performance, the water flow regulator valve might be out of adjustment. The normal adjustment as done at the factory is as follows: On the top of the water flow regulator valve locate the red plastic adjustment screw. Mark the location of the screw with a dab of paint for reference. Turn the screw clockwise (tighten) until the top edge of the screw is flush with the top of the black cap. Turn the screw 2 clicks counterclockwise (loosen). This is the factory spring setting. The bottom tapered screw should be screwed in just snug.

I hope this answers your questions.

Karl

 

[seadoosnipe]

RAVE infatuation....?

It's not an infatuation over the RAVE that people love about them, it's the fact that their Patented design is one of a kind to increase the performance of your engine, without losing efficiency.
Your engine is not going to make the horsepower it's designed to and your fuel consumption is going to be a bit greater than the boats equipped with the valves.
RAVE, Rotax Adjustable Variable Exhaust, is a unique system that allows the exhaust porting to increase as the compression on the cylinders increases, therefore, making more horsepower for less money. .

 

[kustomkarl]

:agree: It's kinda like lets see what happens if we make square wheels. :ack: I just don't like the round ones.