Black sludge coming from my rave valve

[alexpatnode]

I just bought a rave valve off of ebay and I threw the part on and took it out this morning to make sure it worked fine. The ski did great for the first 5 or so minutes then when I killed it and turned it back on, it wouldn't go over 5000rpm's unless I feathered the throttle a bit but even then it wouldn't stay above 5000rpm's for long. I took the ski out of the water and looked at the valve to make sure it didn't melt or anything like that and found black deposits around the valve itself. Anyone have any idea what that is? This is in a 1997 GTX 787

 

[mikidymac]

Typical two stroke oil, fuel and carbon. It happens when the rubber bellows are bad or the springs are not tight.

 

[Matt Braley]

Right. I call it exhaust juice.

Step one is to snug the rave piston up with a 10mm and pull the bellow off. If there is no obvious hole the I clean them up with Purple Power(some members prefer Super Clean). As you push the soap and water rinses around with your fingers look for any little crack cause that's all it takes. With everything squeaky clean you can put it back together and it may last a while.

Step two for the guy who doesn't want to spend hundreds in RAVE parts yet is to get gaskets and O-rings and pull the RAVES out. You will find the fat little O-ring under the housing hard as a rock most the time so the new supple one goes a long way. Sometimes the gaskets under the housings will stay in one piece. If so I'll reuse those a lot of the time because that's just not a leak prone area.

Step three is to bite the bullet. The actual problem in most cases is that the up and down action of the RAVE stem in it's housing wears the stem thinner and the housing hole larger. Once the clearance is too great the heat and the "exhaust juice" get buy and start to kick the bellows off the piston. Eventually the plastic threads in the piston will melt from the heat. A rich running ski makes more juice of coarse.