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  1. #1

    How do I know my Servo Motor is bad?

    Trying to diag the problem on my 01 GP1200r. At full throttle it bogs out. Just replace fuel filter and plugs. My carbs just been cleanded out. Just did my top end on my ski so compressing is at 150psi. I was able to see my coupleens close down at wot.

    GP1200r
    -carbs by Island Racing
    -Protec rec head and reed cage
    -hole shoot kit
    -D plate
    -Primer kit
    -pump work
    -Solas 13/19 by Island racing
    -7,120 rpm


  2. #2
    philip_gpr's Avatar
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    when you shut the motor off the servo motor will cycle once (to clean the valves) if it doesn't cycle either the servo motor or CDI is bad

    I doubt a bogging down is a servo motor - motor will run fine with no servo motor, with no servo the sympyoms would be your peak rpm will just be down several hundred from the normal rpmm (there would be no bogging down, just low rpm)

    You might try pulling the cylinder head and make sure all 3 PVs are working properly when you rotate the PV shaft (sometimes that little set screw that connects the PV arm to the rod falls out)

    or maybe it is the carbs
    Last edited by philip_gpr; 07-20-2008 at 02:53 PM.

  3. #3
    Quote Originally Posted by philip_gpr View Post
    when you shut the motor off the servo motor will cycle once (to clean the valves) if it doesn't cycle either the servo motor or CDI is bad

    You might try pulling the cylinder head and make sure all 3 PVs are working properly when you rotate the PV shaft (sometimes that little set screw that connects the PV arm to the rod falls out)

    or maybe it is the carbs
    It does cycle when I turn it off. Bottom end power is there its just when at half or wot it bogs. When the top end was done my machanic checked that as well and he said it was fine. How can I check to see if it is the servo motor? Am I able to do it with the ski running on the water hose?
    I though it was the carbs at first. That's why I had them cleaned out.

  4. #4
    philip_gpr's Avatar
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    asked and answered, I realize it may not be the answer you wanted, but I don't think bogging down at wot is a symptom of a bad servo motor so I'd suggest you look elsewhere for your problem (especially since the servo motor does cycle like it is supposed to when you shut down the motor)

    if anybody else has any ideas please jump in
    Last edited by philip_gpr; 07-20-2008 at 05:02 PM.

  5. #5
    Moderator RX951's Avatar
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    • does it run up to full RPM's and stay there for a little bit then start bogging out? Sounds like its running lean [starving on fuel] on the high speed adjusters. Just thinking outloud......hmm.....got anymore symptoms?
    • what do your RPM's do when it starts bogging....whats the highest it reads before bogging?
    • What all were done to the carbs? who rebuilt them? Were the rebuilt completely?
    • How were the fuel pump diaphrams ?

  6. #6
    Quote Originally Posted by RX951 View Post
    • does it run up to full RPM's and stay there for a little bit then start bogging out? Sounds like its running lean [starving on fuel] on the high speed adjusters. Just thinking outloud......hmm.....got anymore symptoms?
    • what do your RPM's do when it starts bogging....whats the highest it reads before bogging?
    • What all were done to the carbs? who rebuilt them? Were the rebuilt completely?
    • How were the fuel pump diaphrams ?
    It does run full rpm and stay's there for about 6sec to bog down to about
    3,840-4,100. The highest was 7,020rpm. Yesterday was the first time i put it in the water so I did need to adj the high speed adj cause it was running a bit lean. The carbs where sent to Carl at Island Racing and that was 3 yrs ago. I had them cleaned don't know if it was a complete rebuild. I don't know exactly what Carl had done to them. Since my machanical skills are low I sent things out to the pros like Carl and Jerry. Those are the only symptoms. At 1/4 throttle it runs with no issues. thanks guys.
    Last edited by ADAM12; 07-20-2008 at 11:10 PM.

  7. #7
    Tyrael's Avatar
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    Sorry to hijack your thread, but in relation to PV servos not working.

    Before my rebuild my PV's were stuck closed. They are now free and move well, however the servo doesn't cycle or move (its in the closed position). I rotated my PV's and servo manually to the open position but when i kick the ski over it goes back to the closed position and stays there (and doesn't move throughout the whole rev range).
    I am thinking the servo motor is wrecked from trying to constantly open stuck PV's, but whats the likeleyhood of it being the CDI?

  8. #8
    philip_gpr's Avatar
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    Tyrael,
    it sounds like you problem is either the servo motor or the CDI, if the servo motor cycles when you shut the motor down then best guess is the CDI, if servo motor doesn't cycle best guess is it is the CDI

    If you need any more help on this it would be best to start your own thread

    Adam12,
    sounds like your ski is sick, if you are not comfortable doing you own repairs the best idea would be to take it to a shop you trust - I wouldn't be running it anymore with the symptoms you described

  9. #9
    I know a great shop in Mississippi.......

  10. #10
    do you have an exhaust leak?

    Have you run it at WOT w/o the seat on? When it bogs, check to see if the boot between the exhaust and stinger is leaking. I had the same symptoms, and that was it.

    Do you have a free flow exhaust? Is everything tight there?

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