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  1. #1

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    01 GP1200R REV Problem

    01 GP1200R REV problem

    I just finished rebuilding my engine after having it blow the center piston. I pushed the ski out onto the driveway and it started right up. (A MIRACLE!)

    The problem is that it keeps revving up on its own. It will start at 1500 – 2000 RPM’s and it works its way up to 6000+ RPMs. If I pull the choke, I can bring the RPMs back down. As soon as I back off on the choke, the RPMs will creep back up.

    After doing extensive searching on this site, I came up with just a handful of post talking about this problem. It seems to boil down to two possible issues;

    Air leak?
    Where do I look?
    Engine was just rebuilt. Crank, center piston and cylinder were replaced. I put the engine under pressure and it held 9.5 PSI for over an hour. It actually still had 4 PSI the next day.

    Could there be an air leak between the Reed valve plate and the Reed valve assemblies. There is no gasket there. Should I have spread some marine grease or something else there when assembling? How do I check for an air leak there?

    I did put a new gasket between the Reed valve plate and the carb assembly. Also used new gaskets between each carb and the plate that holds the 3 carbs. How do you check for an air leak there?

    Could the hoses on the carbs be leaking air?? I used all the original hoses. They seemed ok. Should I replace them? How do I check for an air leak there?


    Carb problem?
    Carbs were all rebuilt. I did them myself. They were all very clean when pulled apart. I used all the new parts that came with the rebuild kits. I drilled the high and low brass fittings out. I used the original adjusters screws, but turned the highs out 1 ½ turns and the lows out 1 ¼ turns. During the rebuild, I tested the fuel pump check valves. The fuel pump diaphragms held pressure at 4 PSI as needed. The pop off pressure was consistent at 82 PSI. I used the original 1.2 needle, Gold 115 gr. spring, 95 pilot jet and 112.5 main jet.

    I turned all the Low adjuster screws out 1 ¼ turns. They were originally turned out ½, 1 ½, and 1 ½. Should I put them back to the original settings? Could they even cause this type of problem?

    Misc:

    The idle screw is turned down as it was originally so I don’t think that is the problem.
    Could an air leak in one of the exhaust gaskets cause this problem?

    This forum has been a great help. Without the advice and info on this forum, I would never have attempted to rebuild my engine or the carbs. I am very close to getting this ski working again. Any help you can give me on this problem would be really appreciated.
    Thanks,
    Dennis


  2. #2
    All hail the Chief! fullboogie's Avatar
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    Quote Originally Posted by RetiredWW View Post

    Could there be an air leak between the Reed valve plate and the Reed valve assemblies. There is no gasket there. Should I have spread some marine grease or something else there when assembling? How do I check for an air leak there?
    That's where I'd look first. I just rebuilt my '02, and there were horrendous leaks between the case and reed plate, and the reed plate and the manifold. Use 1211 on every surface in that setup, and use lots of it. Wipe off any excess. And check the reed plate for warpage - mine had a bent corner (not visible to the naked eye) that leaked no matter how much 1211 was put on it. I had to tap it with a hammer and reseal the whole thing. Twice.

    Pressurize the engine again and spray windex all over it. Any leaks will bubble up.

    Check your idle screw again. Screw it all the way out and see what happens.

    Carbed skis sometimes idle really high when you first start them. I don't know why, and mine sometimes does it. But check everything between the carbs and the case.

  3. #3
    If your not doing something, its hard to screw up. stlouisramsfan's Avatar
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    remove your throttle cable from the carns and see what your rpms are then.... if they drop sig... reset that (by adjusting the 10 mm nut) and see if that does it... do a search for pressure test and reeds....

  4. #4

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    That's where I'd look first. I just rebuilt my '02, and there were horrendous leaks between the case and reed plate, and the reed plate and the manifold. Use 1211 on every surface in that setup, and use lots of it. Wipe off any excess. And check the reed plate for warpage - mine had a bent corner (not visible to the naked eye) that leaked no matter how much 1211 was put on it. I had to tap it with a hammer and reseal the whole thing. Twice.

    Fullboogie, Thanks for your reply.
    When I pressure tested the engine, I had the reed valves in, but I did not have the reed valve plate on. Are you suggesting I use the 1211

    1. between the reed valves and the engine case?
    2. between the reed valves and the reed valve plate?
    3. between the reed valve plate and the carb manifold (there is a new gasket there?

    All of the above?

  5. #5

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    OsideBill, Any carb suggestions?

    OsideBill, Anybody!

    Any suggestions on what to look for in the carbs, keeping in mind that I just rebuilt them using all parts in the rebuild kits? They were very clean to begin with.

  6. #6
    WATER WOODY's Avatar
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    Are you running FA's? ANy other mods to the engine?

    ALWAYS pressure test your engine.

  7. #7
    Ya Boy Trevor bajaeater's Avatar
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    lean run away. put a load on the motor. by backing it into the water and starting it. i bet the rpms go down to normal and will be fine. just got done with a ski that did the exact same thing. of course a air leak will do it too. just a thought

  8. #8
    All hail the Chief! fullboogie's Avatar
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    Quote Originally Posted by RetiredWW View Post
    When I pressure tested the engine, I had the reed valves in, but I did not have the reed valve plate on. Are you suggesting I use the 1211

    1. between the reed valves and the engine case?
    2. between the reed valves and the reed valve plate?
    3. between the reed valve plate and the carb manifold (there is a new gasket there?

    All of the above?
    I used 1211 between the reed plate and case, and the reed plate and the manifold. You would be shocked at how much it can leak. Mine would not hold 8 psi for 5 seconds - it bled down immediately.

    Based on your description of starting at 1500-2000 rpm and "working its way up", I don't think it's lean runaway. But maybe so - check idle screw and throttle position at closed throttle, and if that's not a problem, look for reed plate leaks. It may be the problem.

  9. #9

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    Quote Originally Posted by WATER WOODY View Post
    Are you running FA's? ANy other mods to the engine?

    ALWAYS pressure test your engine.
    Thanks for your reply.
    I am not running FA's. Only mods are a Dplate and running premix.
    As stated in the original post, I did pressure test the engine. It held at 9.5 PSI for more then an hour. It still had 4 PSI after 24 hours.

  10. #10
    All hail the Chief! fullboogie's Avatar
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    Didn't you also say you didn't pressure test with the reed plate on? That was the whole point of my post.

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