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  1. #1

    1997 Xp 787 Rejet

    Just squeaked the Mag piston on a new SBT 787. I am considering an aftermarket F/A & jets to help with the mystical 3/4 -7/8 throttle lean condition.

    What is the recommended jetting for a stock 97 XP 787 if I decide to go with aftermarket F/A's?


  2. #2
    96XPSS's Avatar
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    The 3/4 lean conditions are only on 951's. If you seized one, then your carbs are dirty or your SBT engine has an air leak. Either of which you will need to find and correct before rejetting with flame arrestors, because it will just continue to seize otherwise.

  3. #3
    Thanks 96XPSS,

    This was a brand new SBT engine with about 5 tanks of gas through. I replaced all fuel lines, cleaned fuel selector, cleaned gas tank, pressure tested gas tank, chopped plug wires, rebuilt carbs with genuine Mikuni including needle and seat, pop off of 41psi in both carbs...in short, did everything I could to make sure it was running within specifications. Interestingly, the plugs were dark chocolate brown/black indicating a slight rich condition. I will be sending it back to SBT, and look forward to their analysis.

    I am toying with the idea of re jetting and losing the accel pump(which currently works) as I read in "another" forum about greater reliability and less potential lean conditions. I would be interested in understanding said jetting similar to the excellent sticky post for the 951's

    PS: Love the avatar 96 !!!

  4. #4
    Tool Bag water worx's Avatar
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    Jet it to 96 XP spec's & leave the air box on,96-97 both share the same motor just the 97 has a accel pump & with a accel pump it will run slightly lean at 3/4 throttle.

  5. #5
    Thanks Dan,

    I noted that the PTO jet for the 97 XP PTO was slightly larger than the Mag MAIN-(MAG - 142.5 PTO - 147.5) PILOT-65. The 96 XP specs are MAIN-142.5 PILOT-70. Is the increase in a 70 pilot from a 65 enough to prevent the PTO from running lean. After all the 96 XP and the 97 XP are markedly different PWC's.

  6. #6
    To help the lean PTO condition, you would richen the Main, not the pilot. Hence the 147.5 PTO main.

  7. #7
    96XPSS's Avatar
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    Quote Originally Posted by Piranha Performance View Post
    To help the lean PTO condition, you would richen the Main, not the pilot. Hence the 147.5 PTO main.
    This is only if keeping the pump. Otherwise, you need to rejet richer on the pilots to compensate for the lack of fuel otherwise squirted in the carbs by the accelerator pump, at first opening of the throttle.

    If 800 accelerator pump carbs have a 3/4 lean condition it is because they are jetted too lean to begin with. I've never heard of issues before, but Dan has worked on many more than I have...

  8. #8
    96XPSS's Avatar
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    Hey Tippy did you clean the internal filter screens on each carb too? I didn't see you mention that.

    The avatar is my wife...that's all you need to see of her...

  9. #9
    I replaced the filters with new ones. The old filters were not that bad infact, and cleaned up quite nicely in the sonic bath along with the carbs.

    The avatar is my wife...that's all you need to see of her...
    DAMN !!!

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