surging top speed

[kustomkarl]

help help..I just bought a 1997 SeaDoo Challanger. New plugs in it fuel was full when I purchased it so it's about 2 months old, oil injector intact. starts fine on hose or at dock.(not under load) Well on maiden voyage with 2 in boat, started right up, left dock in no wake zone, so it was warmed up. Eased up the gas...wow hit about 45 on dash spedo... Had about 5 minuts of fun playing and it started to slightly surge, and dropped speed down to about 25-30 at full throttle. Headed back to dock still surging. Checked the plugs, fine. Pulled boat out and fired it up at home on hose. Started and idled fine. With the throttle in center position it surged like a carb limit switch would do, so I left it in the lowest position to rince the engine of salt water.I noticed on the pto side Rave valve had dribble of black oil running down... could the bellows on the rave valve need replacing?( I found the same items on similar boat manual) I Have a strong back ground with standup Kawasaki's, as a trained technicion and a racer, but this is my first SeaDoo. Waiting for a shop manual now from our forum. Any help from other owners would be great.
Karl

 

[seadoosnipe]

Bellows!

Yeah, it does sound like your bellows on the RAVE may be blown. But I'm in question as to the surge. I guess it's possible that it could cause the engine to surge back and forth.
The RAVE (rotax adjustable variable exhaust) really only variates when the throttle is given, building up cylinder pressure, internally ported under the bellows to push the valve open. Mine (1997 Challenger) stuck and it caused the engine to seem like it was running with half the power, but there was no surging.
Pull the RAVE valves and check them. You'll likely want to have a can of carb cleaner to remove all the carbon deposits (they should be cleaned annually). If the bellows is blown, you can order one through one of the parts shops we advertise with on the forum's main page. I've personally used one of them and got a good deal on jet pump parts.....
When pulling the MAG rave, there's a quick little trick. The PTO side will come out in one piece after removing the allen head screws, but the mag side rave will be hitting the exhaust system. Pop the clip to the black cover, (careful, theres a spring under the cap) you'll notice in the center of the valve, a metric black nut type fitting. This attaches the bellows to the valve. Get a socket and unscrew this nut all the way. Then remove the bellows section. The rave will remain in the head. It has guides on it so that it won't fall down into the cylinder. Once you remove the cap, then you can just pull out the valve. Put it back in reverse order. Make sure you put both raves back in the same cylinder they came from. I've also found a supplemental guide that suggests to adjust the rave spring tension (red cap) flush with the black plastic cap. Well, I did this and the power loss was horrible, so I adjusted the cap all the was down as the manual first suggested. It responds and runs a lot better.
Give me a holler back if you get stuck.....:hat:

 

[kustomkarl]

Do you think the trickle of oil from under the one RAVE is any indication of it being blown? How do I determine if 1 or both are blown...are they torn or cracked or something? Also is there anything else to service on the RAVE other than the Bellows? I read up on one of the other newer models manual, and it seems like this RAVE valve system is the hot little ticket. One of the supporting venders had a nifty parts break down of the assy. w/ prices like 17.00 each..seemed reasonable for the age of the boat. Thanks for the help! I spent the last 2 days detailing this little beauty, now I'd like to get it wet. lol
Karl

 

[seadoosnipe]

Raves!

Karl, on the bellows, there is a retaining spring that holds it to the valve and on the bottom end of the bellows, there may or may not be a plastic tie strap on it. It shouldn't really be that big of a deal on it. It it's blown, then it may not be operating real smoothly and may leak a little oil that will build up from the engine. When you pull the rave valve, you'll be able to take a flashlight and look into the hole and see the top of your cylinder. The valve is only in those two pieces. The valve and the bellows assembly.
The theory of these valves are awesome. Back when I used to build high performance engines, you could put anything you wanted on the intake side to make it run faster.....i.e, huge Holley carb, Weind intake manifold, etc....but what people didn't realize (or understand) was that to make an engine run faster, it wasn't just what you could put in, it was also determined on how much you could put out. That's why when we built these engines, we'd take off the stock 196 heads and put on the high performance 202's. That's where the rave valves come in. As you start buring more fuel, the raves will slowly open so you can exhaust more gases. The more gas you expel, the faster you can go. :hat:

You shouldn't have to replace anything on the valve itself. If the bellows is torn or cracked (dry rotted) then, you'll want to replace that. When you take it out, you should be able to undo the spring and stretch and push in with your finger to inspect and look for holes. As I said before, when you take off the clip that holds the cap on, there will be a small spring that is inside. Don't let it go flyin on ya!......you might have to go look for it........LOL.....and make sure to clean off all the carbon deposits. Be careful when removing the valve body not to rip the gasket. The internal porting of the cylinder's gas comes into the rave through a little hole in the bottom, through the gasket. So try and be careful not to rip it.
Give me a shout if you run into problems!........