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  1. #1
    Dave in DE's Avatar
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    GP800R big bore kit

    has anyone ever used the 84mm jugs from a gp1300 to create a big bore kit on an 800? effectively creating an 865cc instead of 784cc. would require some carb jet work. but what else? bigger carbs all together?

    any thoughts? just thinking long term project.


  2. #2
    The porting on the 800 jugs is much more drastic than a 1300. So the increase is size will give you minimal gains vs proting the 800 jugs themselves. Contact Lowell Horning, do a search here. Hes the hest when it comes to porting the 2 storkes. Did an 800 10 years ago, and still have a 1300 ported motor going strong from a 2003 ski

  3. #3
    Dave in DE's Avatar
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    the porting is different? thought it was the same based on photos and that the 800/1200 are the same. figured they just added the larger bore to get to 1300.
    thanks for info.

  4. #4
    Fat Man, Little Boat Region8Ultra250X's Avatar
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    scittb is correct.... the 66E / 66V motors shared the same jugs dimensionally but the port timing on the 66E (GP800/800R) motors was preferably better.

    I guess the next question is what are you looking at sticking this in? I mean if you want to go full tilt might as well get two jugs and do a big bore 927 motor. the weak link in these motors is the powervalves. your options on the GP800 are to either run a p/v controller and the wave eater clips or run an aftermarket exhaust and convert to gas valves.

  5. #5
    improvised tmg97gp's Avatar
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  6. #6
    mudslanger's Avatar
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    Better to just go 1200. Everything you can do to that 800 won't equal a stock 1200 with some bolt ones. And you are stuck with the PV servo on a 800 no room for gas valves with stock exhaust.

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