How does the RAVE vavles work?

[Tailgate4jc]

I have read in other post to watch the RAVE valves to see them operate. Well on my GSX Limited has some RPM problems and I am working on some diagnoistic. In the mean time i have the covers of the bellows off and running it with out the seat. At any of the giving RPMs i see no movement of the bellows. Are they open or closed at idle? So does it increase the size of the exhaust port when you throttle up?

Just curious on how these things operate and how they may be part of this problem.

Thanks for any help.

 

[bigJake]

I have read in other post to watch the RAVE valves to see them operate. Well on my GSX Limited has some RPM problems and I am working on some diagnoistic. In the mean time i have the covers of the bellows off and running it with out the seat. At any of the giving RPMs i see no movement of the bellows. Are they open or closed at idle? So does it increase the size of the exhaust port when you throttle up?

Just curious on how these things operate and how they may be part of this problem.

Thanks for any help.

normally they are closed at idle and open at higher rpms as the exhaust presssure overcomes the tension of the spring which holds the rave closed, but since you say you are running with the rave covers off and therefore no spring to hold them closed I think it's a bit hard to say at what point they are opening

 

[bigJake]

can you post a link to the other posts that tell you to watch the raves with the covers off

 

[Dr Honda]

Without the caps... they will probably just open as soon as the engine starts. I've never seen a post saying that you should "Watch" the valves. Personally... I just pop the caps off, and make sure they are free. If they move, and there is no sign of burning... they will work. The RAVE's on the 800 are a very simple device.

 

[Bills86e]

On the 951's the MPEM sends power to the solenoid, depending on where the rpm's are at in the power band, to open or to close, around 4400 rpm's. The Solenoid still uses the pulse pressure from the lower case nipple in applying pressure to the rave bellows. Make sure the lines have No Leaks! The 951 uses a TPS to signal the mpem, but actually plays no part in the raves operation. Your yearly maintenance should
include inspecting the wear on the power valves as described in your shop manual. The ECWI or Water Regulator, will change the timing of when water gets injected into the pipe, which changes the performance a bit. It will not make your boat faster, but it is an aid to the accelleration curve. Typically, the WR red cap is the opposite of where the RAVE caps are set. So, if the raves are adjusted outward, the WR cap in adjusted inward or vise versa. Adjusting the WR spring tension valve will either just delay or speed up when the valve opens.
for 951 engines it should be fully tightened in the cover bore. at that setting the pipe is dried out somewhat allowing the engine to rev higher.Changing the adjustment will only change the amount of water that is injected into the headpipe. Having said that, if you were to actually completely pinch off the water line from the regulator to the headpipe, the exhaust chamber would overheat and melt the hoses.



Bills86e

 

[jerrygena]

Hi, this is my first ski but I work on all kinds of motors. Rave or Power valves just restrict the exhaust more at lower rpms, I guess these motors gain low end power with some back pressure, and open and the rpm's increase via the small hole through the base of the valve, you should make sure the hole is not plugged if your not seeing any movement when motor is running and rpm's increase. On this 787 motor i'm working on, I had to dissemble the valve closest to the exhaust pipe to get it out. Very simple device like the Dr. stated. Now i'm sure if you take the caps off, they should be raised due to the bellows, and with the engine running, without the springs holding them down, they should raise up when rpm's increase. When I got this ski(96gsx) I had to rebuild the top end, looked like the rave valve contacted the rings in one jug and caused the piston to get a large burnt chunk missing, maybe the previous owner didnt releave the ends of the valves when it was bored out, you have to releave the piston end of the valve for clearence so the valve doesn't break the ring.

 

[Dr Honda]

On the 951's the MPEM sends power to the solenoid....

Bills86e

I guess I should have checked to see what engine we were talking about. Sorry.

 

[bigJake]

I missed the "Limited" too. My post probably threw you off Doc - my bad. I was just reading about the 951 raves being operated by solenoids a couple days ago too...