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  1. #1

    Blown Up Super Gp1200r

    hi all,

    i am new to performance skis. i brought a GP1200r super stock from the States and had it shipped back here to Oz only to find it had a completely ceased 3rd cylinder.

    the whole was full of mud. below are the specs of what i have got. i need to get a new crank and piston just wondering if anyone can help me.

    Can the crank be standard as i have been reading about changing the degrees.

    also the kawasaki flat top pistons not sure what model to get the off from what canwork out i need a pro-x stx1100 with a .25 o/size (bore 80.5mm) only markings on the good cylinders are ART, Made in Japan, 25.

    any help would be appreciated.



    Very clean 02 GPR hull. White with blue fairings.With reg
    1200 riva super stock motor with under 10hrs.
    cyl and cases are ported
    Kawasaki flat top pistons
    T/W crank exellent shape'
    Riva gas valves
    VF3 reeds
    Riva heads with 33cc domes all new ring kit
    185 psi
    48mm Novi carbs just done by O-Side
    Fly flame arrestors
    Duel external mikuni fuel pumps with a O-Side water seperator
    Tripple fuel pick up sending unit
    Riva CDI box with triples curves
    MSD 8.5mm coil wires

    Factory racing triple pipes
    New factory water intake water seperator and distabution block
    New O-ring and kevlar seals
    New exhaust springs
    New silicone couplers and clamps
    Have 3 jet works valves 1 for each chamber
    Stock GPR waterbox with blue exhaust tube

    2007 H/O pump with 2" spacer not installed at this time
    Solos D/F 14/20 prop
    Sho exit steer nozzle
    All water exits are piped out rear of hull
    Pump shoe sealed
    Pump tunnel has a pre made kit 5200 in for strength
    R/D 1200 intake grate
    R/D ride plate lite mod
    stock tabs
    Riva black sponsons
    New M-line seat cover to go with it
    Pro Taper bars with yami pad
    Riva finger throttle

  2. #2
    Prism's Avatar
    Join Date
    May 2007
    "New" Jersey
    Quote Originally Posted by GPR-AUS View Post
    i need to get a new crank and piston just wondering if anyone can help me.

    Can the crank be standard as i have been reading about changing the degrees.
    The crank you already have in the ski is probably standard. Yes the stroke can be changed to make a larger displacement engine, but it seems you have every detail from the previous owner and they sure would remember installing a stroker crank. Its expensive, and a big selling point if it had one. As far as changing the "degrees" as you say, this is done with an off set keyway that is installed in the crank. The keyway is the modified part that fits into the crank. The crank is NOT modified to make one fit. Its also doubtful you have a modified keyway in that ski. In addition to the reason above, the keyway is usually used on EFI skis or 1200 skis that don't have an Advent, Riva, or other CDI box. The reason being that the sole job of a modified keyway is to advance the flywheel a number of "degrees" so the ignition picks up the signal sooner relative to an unmodified engine. This results in an ignition that is "globally" (everywhere) advanced over stock. With a modified CDI box, you can program the advance curve you want. As stated in your description, your ski has a Riva CDI box with triple pipe ignition advance curves. This makes a keyway unnecessary. As far as the pistons-- you listed the over bore at .25" which is one quarter of an inch! (6.35mm) Did you mean .025" which is .635mm or .0025" which is .0635mm? Hope this helps.


  3. #3
    Yeah thanks for that alan.

    Greatly appreciated now i just need to know what sort of kawasaki piston is in it. the markings on the piston are ART,25, which i assume it means .25mm oversize(.5mm in total) my barrel measures 80mm tight. my piston measures the following:
    Wrist pin 22x65mm
    Piston Diameter 79.5mm
    Piston Height 78mm (appears to be shaved at the base)

    any further help would be good.

    im thinking its off a kawasaki stx1100


  4. #4

    Join Date
    Jan 2006
    Texas City, Texas
    Perhaps you should talk to the original owner/builder to find out exactly which pistons were used and the best source to buy another.

    It is also important to find out what triggered the distruction in the first place so that it may be corrected.

  5. #5
    Join Date
    Oct 2006
    speak to bren on here , he may be able to help you out as he has a SS 1200 as well and is local (QLD)

  6. #6

    any idea how i get in contact with bren. new to this forum still trying to work it out. cant get any help off the owner of the ski unfortunetly.. trying so want to get this things running before summer.

  7. #7
    You have OEM SXI/SXIPRO pistons at 80.25mm in your ski.

    Those motors, race flat tops, used OEM / ART, Standup ski pistons.

    Your bore should measure at least 80.25 but really about 80.35 or so for clearance

  8. #8

    i measured all the bores again and they are 80.0 tight no chance of them being 80.25/35.. i checked the cylinder again and its 79.5 forged.

    any ideas if the SXI cylinder will still fit.

    anyone know how to cntact gprfrank he built the ski originally from what i can gather. i tried to pm him with no luck.

  9. #9
    all you need then is OEM Kawasaki 80mm big pin pistons 1996-2002 Twin motors. ALL THE SAME.

    Now you may need to just kiss the corners of the pistons on the bottom because they sometimes hit the crank. Riva use to sell them preclearanced. It only take a file/grinder and sandpaper. Maybe 5 minutes a piston.

    99% of all race boats from 2000-2005, when GPR's were the SH*&, had these Kawasaki pistons in them. Even the cylinders that have iron sleeves these pistons were used.

  10. #10
    thanks MTR Head ill give that a crack.

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