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  1. #1

    GSX first run on lake, loss of rpm's

    So i decided to take my jet ski out and pray i don't fall in the water. I bought this jet ski last fall and have done a lot of cosmetic work to it and minor stuff like cleaning the rave valves (obvious previous owner never did) and fixing the vts system. So today i wanted to see if there were any major problems i needed to fix before real lake season hits here. It acted a little goofy at first, but after about 10 min the ski was working normal. The only problem is I am maxing out at around 6500 rpms WOT (and about 52mph). I am pretty sure it should be around 6800. My question is, where do you generally start to find lost rpms? I am guessing wear ring, exhaust leak, and carb tuning? Also, any idea how many mph 300 rpm's would even add if at all on the top end? Thanks in advance!


  2. #2
    Work Harder, Millions on Wellfare Depend On Us! ultramaxracing05's Avatar
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    is it a gsx limited or just a 787?

  3. #3
    johnboygtv's Avatar
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    Hi check to see if your rave bellows havent come off,i had one off and lost abit of power

  4. #4
    thanks for the quick replies. Its a 787. Also what part are the rave valves is that, where the metal elastic band goes around it? johnboygtv what is your max rpms and speed?

    Thanks!

  5. #5
    flyin' the friendly skies airbornexp's Avatar
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    look at your pump...wear ring,carbon ring, damaged prop ext. you could also, as mentioned above, have a bellow off the rave. take off the black cap with a red centerand there are rubber boots with a spring ontop of the black cap andone around the bellow. Id start there...

  6. #6
    Thanks for the help airbornexp! Ill check those out either tonight or tomorrow. I appreciate the tips. My buddies Yamaha xl 1200 (130hp 3seater no powervalves) out runs me by about 1mph, but i am pretty sure this gsx should be faster than it. Anything i could do to get a little closer works for me!

  7. #7
    jsirois831's Avatar
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    Quote Originally Posted by johnboygtv View Post
    Hi check to see if your rave bellows havent come off,i had one off and lost abit of power

    second this...that happened to me...i cleaned the RAVEs and same thing happened to me...i was dumfounded until i took the time to actually look..lost about 300 RPMS on the dot

  8. #8
    Quote Originally Posted by airbornexp View Post
    look at your pump...wear ring,carbon ring, damaged prop ext. .
    Usually if your wear ring is bad or carbon ring is bad, your RPM goes up, not down......(High or normal RPM, but lower than expected GPS...)

  9. #9
    johnboygtv's Avatar
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    Quote Originally Posted by steelers87 View Post
    thanks for the quick replies. Its a 787. Also what part are the rave valves is that, where the metal elastic band goes around it? johnboygtv what is your max rpms and speed?

    Thanks!
    Hi
    im running about 7000rpm,but ive rejetted my carbs with an R & D f/s and 85-87 nozzles. if your bellow is off,juck the metal elastic band and rap some wire round it,but not to tight so it doesnt cut the bellow,works for me

  10. #10
    hey guys checked the rave valves and the bellows are all on correctly. I was trying to think where to head to next. I am thinking i should check for an exhaust leak before moving to the high speed screw? Also one quick question, what exactly does that 3rd rave valve do on the exhaust?

    Thanks for your time!

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