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  1. #1
    race24x's Avatar
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    Weird performance

    Out on the lake with my ski I fouled a plug (second one in 10 rides) I thought it maybe from idling out after initial start not sure yet. The weird part of it all is riding across the lake wide open it seems to ride really well. go to 3/4 1/2 throttle and it starts to feel like it is fouling a plug or loading up. Lacks a little power. If I start spinning it around goofing off sometimes it runs well others it loads up and takes a while to come out of it and run well again. Wide open plug chops look pretty near perfect. Its hard to tell without a boat beacuse I have to idle in to the boat dock for about 100 feet. Is there something that would affect 3/4 1/2 throttle that I could look at. Today I was going to check the fuel pump and fuel selector switch I have read they have issues sometimes. My fuel pump feeds under the carb rack one line but splits to 2 different spots on the carb rack right and left. Any suggestions?


  2. #2
    Never Time To Ride antoniodef's Avatar
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    I assume your saying it's hard to check a plug chop without a boat to do it on. I just take the ratchet with me. Pop the seat off and toss it in the water and stand over it and pull my plugs. The seat floats. You will get better reads pulling the plugs after a 100 yd WOT then after you idle back to the dock.

  3. #3
    casey67's Avatar
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    Antoniodef is 100% correct. 100 yards is more than enough to change the plug color,you are checking the idle mixture.You need to check plugs after running wide open,hit the kill switch,keep throttle open.

  4. #4
    ph2ocraft's Avatar
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    Race, what were your MAX RPM's?
    If you lost some RPM's and the boat falls on it's face my guess is you're running lean in the mid-3/4 range??
    Possible restriction in the hoses, pump, leak at fuel selector switch etc.
    Get a good plug chop and/or piston wash and let us know what you find.

  5. #5
    race24x's Avatar
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    I will try some plug chops tonight and see what I can get. I thought that the plug fouled was an indicator it was running rich. Plus it seems to load up and then comes out of it when holding it wide open after about 20 seconds or so.

  6. #6
    casey67's Avatar
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    Checking the plugs when the problem happens will stear you towards rich/lean.More fun checking it on the water,than in the garage.A compression check will also help with the plug fouling condition.As ph2o suggested,it's always good to check the hoses/switch/pump on something old,will cause alot of problems rich/lean/stall/hesitate/lack power/stumble.

  7. #7
    ph2ocraft's Avatar
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    Quote Originally Posted by race24x View Post
    I will try some plug chops tonight and see what I can get. I thought that the plug fouled was an indicator it was running rich. Plus it seems to load up and then comes out of it when holding it wide open after about 20 seconds or so.
    Here's an example of your scenario. IF the return restrictor were plugged the pressure in your carbs would be high. High enough to open your needle/seat so at idle the fuel dribbles into the venturi and.....fouled plug during idle/low speed.
    If that same dirt/garbage etc. is blocking the fuel filters it will create the flat spot or hesitation as the carbs starve for fuel (dangerous to the engine) as this is when the engine demands the most fuel (advanced timing/engine under load etc.). Now you're at top speed where fuel requirement is a little less but you lose RPM's because you don't have the fuel volume required to maintain the speed-you are running lean and it will cause severe detonation and bye-bye piston.

    Now I can certainly be wrong but with your input we can get a better idea as to your running condition at WOT, no more than 100 yards at WOT should do the trick.

    Let us know what you find.

  8. #8
    race24x's Avatar
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    Where are the fuel filters etc and the return restrictor I can check all of that to make sure its all OK

  9. #9
    race24x's Avatar
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    OK I took it out again today and found it runs pretty good until I start horsing around and spinning it and things like that. When I pull the seat I noticed the CDI box had some splash on it and so did the motor. I think I have to pull the CDI box apart and see if there is some water insode from where I sunk it once. It only seems to leak when I am spinning it around it seems like the seat seal is leaking somewhere. It loaded up and was fouling a plug ran it wide open for about 15 seconds it clears right out and runs good again.

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