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  1. #1

    97 787 RAVE keeps breaking

    97 XP (787), the "exhaust piston" which has the threaded boss that the slider screws into keeps striping after about 3-4 hours. This has happened three times now. The first time I thought it was just old and had too many heat cycles. Now two new ones have broken. All of this started after I put a Group K sleeper kit on the motor. Group K machines the RAVE to match its porting, but tells me that it is not hitting the piston. What are the most common possibilities? It is always the MAG cylinder....of course, the PITA one. Is something worn, loose or what? Any help on what to check appreciated.

  2. #2
    This is how I run a jetski shop in the desert nmpeter's Avatar
    Join Date
    May 2008
    Elephant Butte New Mexico
    do you mean to say that the blae is coming loose from the plastic cap?

    The rave valve body may be worn and allowing too much exuast gas pressure to enter the bellows

    If the bellows is not connected with the oem springs on BOTh sides ( almost every doo I get in for rave work somebody mickley moused it with zip ties) there will be exhaust leakage and hot gas making it's way thru the bellows will melt the plastic cap.

  3. #3

    Join Date
    Mar 2006
    blade and housings wear out. Measure the stem and measure the opening in the housing that the stem rides in-- then measure new parts.

  4. #4
    Well, well, well. I could feel that the slider and the exhaust piston were not screwed together and assumed it was the threaded boss as the other 2 were. It was not. I pulled the Mag valve and the stem is snapped and one of the corners is missing from the valve face. How that piece got out without snapping a ring or breaking the piston, I don't know. I assume that it went out the exhaust port. I can't help but think that the RAVE is getting hit by the piston, but how? The valve does not hang out in the cylinder. It has not been bored. I checked during assembly and again after the first exhaust piston was broken.

    Prior to the stem breaking, I was going to check the stem for wear and the base that acts as a valve guide, but no point now. I will need a slider and will go ahead and replace the base. I still am concerned that something is hitting the valve somehow. I have dropped the slider in alone until it stops and spun the motor with no feel of impact. I don't get it.

  5. #5
    Mod less, ride more! troyheb's Avatar
    Join Date
    Jul 2007
    Nederland, Texas
    If I remember correctly, even if the stem breaks as yours has, it will not hit the piston.

  6. #6
    surferd15's Avatar
    Join Date
    Jun 2007
    Fort Lauderdale, FL
    There was an issue with older raves breaking at the stems, there is a newer style that has slots in it, mostly sold by SBT, which are not suppose to break. I had the same issue with one on the PTO side. I replaced it no issues since then.

  7. #7
    This is a 97 motor with OEM sliders with the slots. I can understand how the corner could break off with metal stress and heat cycles, but why would the stem break where it meets the slider? In the closed position, the stem failure area is even with the guide base. I have never had a RAVE break, just don't want to throw another one in there and have it happen again.

    Speaking of SBT, I have always used OEM parts. Should I consider buying the slider and bases from SBT?

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