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  1. #1
    smoofers's Avatar
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    GP1200R Won't Rev Past 5k

    I have been working on a buddy's '01 GP1200r. I put an SBT engine in for him and rebuilt the carbs, pump, converted to premix, D-plate, etc. about 7 years ago. The ski sat for the last 5-6 years and now I'm helping him get it running again. Here is what I have done so far:
    • Rebuilt all three carbs and accel pump with genuine Mikuni kits and new genuine Mikuni N&S sets. Pop off averaged about 80 psi for all three carbs. Jetting is stock (117.5H, 95L) and carb screws wer per the latest Yamaha bulletin (Mag and PTO 1.375H, 1.5L and Center 1.375H&L).
    • All new fluel lines (Honda black rubber OEM)
    • New fuel filter and check valve
    • New plugs
    • Old fuel tank sucked out and clean
    • Replaced the dash display with a used working unit
    • Blew out all cooling lines and verified flow
    • Inspected reeds (visually look good)
    • All new gaskets/O-rings where necessary (exhaust, intake etc.)
    • New, fresh battery
    First time I put fuel in the tank and went to start it it fired right up. I took it to the lake and throttle response seemed good while I was putting through the long no-wake zone. When I got out of the no-wake, I pulled the throttle and the ski would only get up to about 4-5k RPM and sounded like it was hitting the rev limiter (sputtering). I suspected the rubber apron on the fuel sender assembly was leaking and keeping the fuel tank from pressurizing. Sure enough, I put some air pressure in the tank and the sender was leaking air.

    I replaced the fuel sender with a used unit and pressure tested again. Good. Holds pressure. Took the ski back out and still the same issue. Won't rev past 5k RPMS. Next thing I suspected was the YPVS servo not opening the power valves. I replaced the servo with a used unit (adjusted per the manual) and have verified it is opening when the throttle is pulled on the water. I also pulled out the middle PV cap to verify that the shaft was indeed opening up the valves. It is. Ski still won't rev past 5k. I also tested compression and it's a 117-120 in all three holes.

    At this point I'm stumped and just want the ski running and out of my garage. What am I missing?
    Last edited by smoofers; 09-18-2020 at 08:32 AM.

  2. #2

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    Sounds to me like the PV servo is stuck.

  3. #3
    smoofers's Avatar
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    Quote Originally Posted by Jonesyfxr View Post
    Sounds to me like the PV servo is stuck.
    That's the crazy part. Riding the ski with the seat off you can clearly see the wheel on the PV shafts reacting when I apply throttle. Definitely not stuck...

  4. #4

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    Hmmmmmm..... interesting

  5. #5
    jeffg426690's Avatar
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    Cpl things?:
    Verify pv valves turn freely by hand, remove cables and turn the wheel. Should be smooth and easy, no sticky spots. They may need to be cleaned.

    Also had a bud w a similar issue, high speed jets needed to be replaced cause of fuel varnish that you can't see.

    Just a few thoughts. Keep us updated and good luck!

  6. #6
    smoofers's Avatar
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    Quote Originally Posted by jeffg426690 View Post
    Cpl things?:
    Verify pv valves turn freely by hand, remove cables and turn the wheel. Should be smooth and easy, no sticky spots. They may need to be cleaned.

    Also had a bud w a similar issue, high speed jets needed to be replaced cause of fuel varnish that you can't see.

    Just a few thoughts. Keep us updated and good luck!
    The shaft turns smoothly by hand, no sticky spots...

    I REALLY don't want to pull the carbs again, lol. It might come to that. I ultrasonic cleaned the jets in naptha, they came out sparkly.... I don't know what else to check at this point. Thanks for the replies. Keep the ideas coming.

  7. #7
    dockwalker's Avatar
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    Did you check fuel flapper lid at bottom of pickup?

  8. #8

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    I never thought about the fuel flapper in the tank.

    Another thing I thought of, do you have PV couplers?
    If not maybe the PV’s aren’t opening all the way?


  9. #9
    smoofers's Avatar
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    Quote Originally Posted by dockwalker View Post
    Did you check fuel flapper lid at bottom of pickup?
    No I haven't. What could be wrong with it?
    Last edited by smoofers; 09-19-2020 at 06:11 PM.

  10. #10

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    It hangs up and limits the fuel flow

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