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  1. #1

    Gpr flattop piston (Kawasaki) question

    I'm working on a superstock GPR that had 80mm Wiseco R&D dominators (Kawasaki flattop style forgings)

    I would like to put cast pistons in it like Kawasaki OEM or Niks Pro-x cast Pistons. However I have discoved that the length of the OEM Kawasaki piston is 78mm from the top timing edge to the bottom of the skirt. This is NOT enough length. The piston will not seal off the crankcase when it is at TDC. The Wiseco or R&D piston is 79.4mm long but I don't want to use Wiseco's again if I don't have too. The piston needs to be longer than the stroke of the engine in a two-stroke

    I notice in this picture
    Steve is putting in Pro-X kawasaki 80.25 pistons #4491.

    Does anyone have a set of Kawasaki Pro-x pistons that they could measure the full skirt length ? Timing edge to the bottom of the skirt.

    And no - I do not want to covert the ski over to Yamaha pistons - It wont work the cylinders are decked, heads are designed, all for Flattops.

    Thank you,

  2. #2

    Join Date
    Dec 2005
    new jersey - bronx
    I use stock kaw.. pistons from a 1100 flattops. But you have to cut the sides of the skirts or it will hit the crank journel with the kawi pistons.. Also riva sells them pistons already cut and ready to go.. 80 or 80.5.. ProX work great too. Them you can get in .25 if you need..

  3. #3
    do you let them come above the exhaust port at TDC ? or do you have your piston top below the exhaust opening at BDC ?

    Yes - I know about the cutting on sides. I'm just trying to find a longer piston than the OEM kawasaki

    Do you have one to measure ?

  4. #4
    Happily Self-Employed WFO's Avatar
    Join Date
    Nov 2005
    Houston, Texas
    Call Tim Judge... he has some experience with that set up.

  5. #5
    Yes - but I thought I'd try here first - All I really need now is a Pro-x piston measurement of a Kawasaki Pro-x

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