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  1. #1

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    Jet Works valve on GPR 800 need advice

    Hey Guys,
    Planning on installing a Jet Works valve on my 01 GPR800. Have seen many post about the install on 1200's , but no 800's. Would the process be the same ? Or would I install on the hose that goes from the head to the pipe ? Any help would be great !!
    Thanks


  2. #2
    A child of five would understand this. Go get one. pierowman's Avatar
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    Should be the same as the 1200's.

  3. #3

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    The 800 needs an additional adapter that the 1200s don't need. This thread talks about it:

    http://www.greenhulk.net/forums/showthread.php?t=106635

    So does this one:

    http://www.greenhulk.net/forums/showthread.php?t=67971

  4. #4

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    Called Art and has no more adapters for the 800 , Does anyone have one , or this there another way I could install the valve ? Looking at the digram in second link, where would the water bypass hose go to ?

  5. #5
    Stock GP800r water by-pass design v. Stock 1200/1300 water by-pass design = 800 better hole shot by far. Not telling you what to do, and everyone has their own tuning opinions, but what I would do (and did to my 800) for a better hole shot was mill the head (from 130stock psi to 155 without messing with squish), flame arrestors and FF tube and prop (add reeds and stuffers too). Any combo of those bolts-ons will do... .

    IMO part of the reason that there are not alot of performance kits for the 800 is that the originial design was pretty good. Study the stock water by-pass routing and the shape of the exhaust and you'll kind-of get-it. I don't think the jetworx is worth it on an 800 IMO.

  6. #6

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    Jim,
    do you remember how much you milled off your stock head ?? Have been planning to do that , seems now would be a good time
    Thanks

  7. #7
    You need the adapter for this to work. The design of the end of the stinger is totaly different then the 12/1300's. I have been sending everyone Arts way the last 2 yrs for the last couple o
    f adapters he had.......Should of made commision on those things......lol

  8. #8
    Quote Originally Posted by [email protected] View Post
    Jim,
    do you remember how much you milled off your stock head ?? Have been planning to do that , seems now would be a good time
    Thanks
    William, I was able to shave .030 which is the limit without changing the squish. The lip on the head was fairly tall (.030) so I took all of it off and ended up with the minimum recommended squish clearance between .025-035 (I'm also running only one gasket). I did notice the entire stock squish band area on the 800 was wider than my 1200 and 1300 heads, which may have something to do with the resulting psi bump from 130 to 155, from just shaving only the lip off. Generally, wider squish = low-midrange power/higher turbulence in the chamber, as I understand it.

    BTW, Group K claims the 800 motor has a wide power band; I have to agree. The 800 is an awesome motor, but they should have kept the lighter hull (100lbs.) from the earlier years between say 98-2000 IMO.

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