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  1. #1
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    Just bought a gp1200 questions..

    I posted this in the wrong section a while back and i forgot about it so i figured ide just start a new one in the correct area

    I just picked up a 98 gp1200 for a steal of a price for a buddy but im trying to find some information on it...

    he said the previous owner rebuilt the motor with higher
    compression pistons, requires 93 octane. (any reason as to why?) Looked in the paper work and it had a invoice from Group K. but all it says on there is "gp1200 pistons and cylender bore, cylinder size to pistons provided. Head mod(sleeper kit)

    aftermarket ride plate
    Aftermarket water inlet grate
    - he disconnected the oil pump and am
    running pre-mix, has a Primer bulb
    installed in the factory choke
    - Nu Jet impeller
    Adjustable sponsoons for cornering.

    Does any one now anything about group K and these mods done by them?

    i guess my question is can anyone name the "aftermarket ride plate, and water inlet grate" and can you notice if anything else has been done to the ski that i dont know about? He got it in on trade and then just sold it to me so theres really not much information. Any recomendations on the next step for this ski? Sorry im a newb when it comes to skis its an absolutle blaste to ride and does 73 on the guage on the dash (im assuming 67 on gps ) would love to hit 75 in this ski.

    Also it says required 93 fuel, my local lake doesnt offer 93 in premix IF i have to run 93 is there anything i can do to a 90 fuel to make it up to 93? (fuel additative? octane booster) I just wanna make sure i dont pop the motor.

    Also i have been searching this forum...holy information overload


    Here are some pics









  2. #2
    Yamaha artisan Cutlass's Avatar
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    The higher compression comes from the cylinder head mod that Group K does, not the pistons. Group K machines the head and reshapes the combustion chamber so that it is smaller and gives higher compression.
    You'll have to get a picture from underneath for us to ID the intake grate (where the water flows into the jetpump). From the pic, the ride plate looks like a stock one. Get a better pic of the ride plate, intake grate, and some pics of the engine.

  3. #3
    Yamaha artisan Cutlass's Avatar
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    Oh and the sponsons are stock too.

  4. #4

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    Quote Originally Posted by 04SRTurbo View Post
    Also it says required 93 fuel, my local lake doesnt offer 93 in premix IF i have to run 93 is there anything i can do to a 90 fuel to make it up to 93? (fuel additative? octane booster) I just wanna make sure i dont pop the motor.
    ]
    Do u have a dock slip? Get a few fast flow fuel cans and fill it up before you go out. Otherwise I would just get 93 octane from the gas station on the way to the lake.

    You said they don't offer 93 in premix... Do they offer 93 by itself? Carry some oil with you in a bottle and add it accordingly.

    Ride plate is the stock 97/98 plate. It is longer than the 99 stock plate. Get a oil of the inside the hull and underneath for further ID. Chances are the intake grate may have a name stamped on it.

  5. #5
    New to the Water Toy's
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    thanks guys i appreciate the help

  6. #6
    Myself's Avatar
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    I would get a gauge and do a compression check before worrying too much about fuel octane. We don't know for sure where it is at right now. I shaved and re-shaped my head, but with the porting it kept my compression down and I can run 89 with no problems.

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