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  1. #1

    787 top end tap????

    Rebuilt the entire engine in the 97 GSX and runs great after tweaking the carbs. Had it out for the third time a few weekends ago, but it's first long run all day. Ran great all day, had premix in the tank as well as the oil pump, oil pump really flows when the cable opens it up. Can see it moveing oil a 1/4" at a time when the pump lever is rotated open. Later in the day started dying out at WOT and the "oil low" light was on but tank still had oil in it (prob old sensor) and it was smoking..

    Not sure what would cause the WOT dying but if you backed off it would run at 3/4 or better.

    Only prob now is I hear a "tapping" very light seems to be coming from the top of the piston/cylinder head area. I pulled the raves and cleaned them up well, seems like the tapping started after that, could be wrong though. Changed the plugs also after the break in plugs, but they are smae model # as the others standard NGKs. Not sure what the deal is, best idea is to pull head adn check pistons??

    Any ideas????
    Thanks guys.


  2. #2

    Join Date
    May 2010
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    Hello,

    I am not a PWC engine builder but I do build Go-Kart racing engines. You always have to brake an engine not. Never run full thorttle and always change your RPM's for the first 3 hrs. So mybe you have bent or broke something. But sure some of the others can give you better answer. Good Luck.

  3. #3
    good point. I did run a full tank through the motor with 50% premix and the oil pump going too. This was the fisrt long outing but the mixed tank was run thru it doing the rpms and never staying at an rpm spot long and no WOT till the first tank was thru. Just can't figure it out since there isn't much there to make those moises unless something is touching, and if that were the case then I would expect it to just smack and then stop?

  4. #4
    So hear are some pics of the pistons and cylinders with the head off. Other than the overabundance of oil burn on the pistons from richened fuel there aren't any marks on top of the pistons from contact with the plugs or the rave valves that I can see. Still really can't seem to figure that noise out unless it is part of the rave assembly rattling? It happens at idle. Any ideas?








  5. #5

    Join Date
    May 2010
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    Savannah, GA
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    umm tell your in salt water.

    As for the noise make sure it not your prop./wear ring. Engine looks good to me. Did you look at the head to see if there is any marks on it? and your plugs was not closed correct? If you ran a hole tank out of it before your starting playing hard you should be fine. It could be the crank but I dont know.

  6. #6
    Yeah salt water, dude before me didnt do anything in the form of maintaining this thing. It has been a total rebuild, honed cylinders, new crank, pistons, etc.. I have a whole long thread on the rebuild. I had to grind out all the water passages etc..

    Yeah it had the whole tank of premix and the oilpump run thru, used mineral oil not synthetic.

    Here's the head and plugs. These are newer plugs than the break in plugs but still had some premix running thru them.







  7. #7
    retro jet's Avatar
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    Jun 2009
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    Somebody correct me if I am wrong. I got time for a quick answer. It looks like the darker piston leaned out. You had some Deto, knocking the carbon off the center of the piston. That is on your grey plug. The brown plug looks good.
    See this...
    http://www.greenhulk.net/forums/show...89-Piston-wash

  8. #8
    Thanks for the response. That would make sense from the pics. How owuld I get detonation, and wonder why it would have leaned out? Oil line popping off cause that?

  9. #9
    retro jet's Avatar
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    Detonation isn't right. Pre-ignitition? Pinging. Did you check for air leaks when you built up the engine? It isn't lack of oil, but lack of fuel.

  10. #10

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    I got a tap in my engine at idle after cleaning my rave valves. I guessed that it was coming from worn rave valve slides. Just saying.

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