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  1. #1

    HELP!! 1991 waverunner 650 lx

    hey guys i am building a "jet jon" with a waverunner motor and jet. i have sucessfully installed the pump and i am currently trying to get the motor running. the motor is a 1991 model but it looks to have a 1990 carburetor. ive cleaned and rebuilt the carb. and have tried to tune it up but still wont run right. do yall think it is my reed valves? they arent broke but how would i know if that was the problem? and also would a carburetor off a newer waverunner would such as a 1995 model work? the motor idles fine but just doesnt have any top end. thanks guys P.S. i dont everything about pwc's just enough to work on them so im willing to hear any ideas or advice


  2. #2

    Join Date
    Aug 2006
    Location
    Orange County, Ca
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    Did u do a compression test? If so what are they? Your reed should be fine if they aren't chip or warp. Is the ski bogging at wot?

  3. #3
    Each cylinder has 100 lbs and it wants to bog down when I give it full throttle

  4. #4

    Join Date
    Jul 2011
    Location
    Galveston, TX
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    21
    100lbs is low, but should idle as you said before... to check your reeds, you will need to pull them out and spray lube into them to see how much, if any, is seeping out around the reed. usally with no rust on the cage, it shouldnt seep much if any at all, and if it does you might need a new or newer used reed cage.

    Based on the info you gave though, it doesnt sound like thats the issue, what i would do is look inside your carb and determine your pop-off spring. There are a few different ones you can use to richen or lean the motor out. with that being said, pull off the diaphram and under that is the arm the moves the needle in and out of the seat and is regulated by that spring, i would assume without looking at it you would need to go 1 size higher to get the throttle response back to right. ie. if your using a 65g spring you might want to try a 80g spring, ect. And yes these are cheep.

    also if that is the case you should notice a blacker plug after running it then normal.

  5. #5
    how many pounds should my cylinders have?? will it still run right with only 100lbs or it that a serious problem??

  6. #6

    Join Date
    Aug 2006
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    Orange County, Ca
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    Between 115 to 125 is ideal

  7. #7
    so do you think i a new motor? here is a little video of what im building and i found a carb on ebay off a 96 650. it looks like it should bolt up do you think it will. mine is not oil injected and dont know if that would make a difference or not.

  8. #8

    Join Date
    Aug 2006
    Location
    Orange County, Ca
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    You don't need a new motor just rebuilt the top end. And inspect ur crank and bearing since ur at it

  9. #9
    so all i need is new pistons and rings or do i need cylinders too?

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