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  1. #1

    Unhappy I'm Stumped, Powervalve Problem?

    Hi Everyone!

    As my first post, i'd like to say. I've been lurking for a long time and you guys have helped me out a ton with my ski's without knowing about it and I think I have finally come across an issue that has most definitely stumped me. (Sorry about the long post, but it'll answer a lot of questions you guys may ask)

    I bought this ski about a year ago, its a 2001 Yamaha GP1200R, it's been modded and neglected and has a bunch of Pro-Tec mods on it, Pro-Tec Intake Grate, Ride Plate, Solas 13/19 impeller, Pro-Tec Turbo Exhaust Tube, Pro-Tec Heads, (i assume the pro-tec hook up kit and wake up kits were installed)... the ski runs great except it tops out at 57mph(GPS).

    This ski with all these mods, I was thinking should run a lot faster than that. Everyone was saying these ski's really give a pull from the power valves as they opened up around 5,000 rpm and I didn't notice this at all and I also noticed my RPM was around 6300-6500 tops. I checked the compression and it was good. I checked my pump, impeller and wear ring etc, that was all fine, I also installed the seal kit which made a big difference in low end and mid range and I checked pretty much everything... and lastly I checked my power valves and this is where things blow my mind.

    - When the powervalve servo is plugged in, top speed is 57mph, top rpms (6300-6500).
    - When I unplug the powervalve servo and manually turn the powervalves open, I feel the pull everyone is talking about and my ski tops out around 63mph and the RPMS top out at 7000-7100ish. Which tells me that's what the problem is! So I know my issue is with the power valves not opening, but why?

    So... I took the servo wheel off and checked the cables, they are nice and lubed and they have no problem moving the power valves open and closed so I know the valves aren't sticking or stuck.

    When I test the servo as per service manual, the servo checks out. If I fire the ski up and shut it down, the servo does an open and close however it did do some weird jitter and clicking after the check, so I thought, well maybe it is the servo since its acting strange, there might be a chance the servo is faulty.

    So yesterday I got a new servo, put it in and..... it does the same thing as far as performance goes(the new one doesn't jitter or click, so I assume that was part of the problem but not the whole problem). But I am still stuck at 57mph tops with rpms running at 6300-6500. The servo moves as expected on a check when i shut the ski off... but I believe it doesn't open the valves as it should when i'm at speed. I tried to check to see if I could see the PVs opening while running the ski without a seat, but it was too hard to tell, I couldn't see any movement, but it was all shaking around so it might have moved, if it did, it wasn't enough to notice it move.

    I also checked the slack in the power valve cables and I checked to make sure they are adjusted properly, they are 100% perfect according to the service manual.

    Now I'm stumped and have nothing else to check, anyone have any ideas?....

    I've read posts about it being the CDI?...... I have no clue on that part, does the CDI control the power valve servo? Can anyone tell me what tells the power valve servo to open and close?... I'm guessing that is where the problem is.

    Thanks in advance!


  2. #2
    Prism's Avatar
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    Make sure the powervalves are at least adjusted as per the shop manual. They may not be opening fully or may be opening too much if the cables are not adjusted correctly. Ride the ski with the seat off and the powervalve servo ruber cover slid back. See if the wheel is turning when the rpm increases to 5 grand. Give that a shot and let us know.

  3. #3

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    Agree. Also to make it a little easier to see, mark the power valve wheel at full open and full close against a reference mark on either the cable mount or cylinder (if that makes sense) with a bright paint. Other thing to double check are the connectors for any sign of corrosion

  4. #4
    theprophet's Avatar
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    Check the couplers on the power valve shafts if you haven't already...

  5. #5
    Install a yellow zip tie around the coupler shaft and ride it with seat off. Go to max throttle and see if the power valves open.

  6. #6
    You could also be missing a power valve. The valve body and shaft can separate. The valve body can exit the cylinder with minimal damage. Only way to see that is to remove the head. Happens all the time.

  7. #7
    Hey everyone, thanks a ton for the input. I've made some progress on this issue. After some troubleshooting, I replaced the servo and I replaced the CDI. Now this is once again where things gets weird. When I first plug in the servo, the servo does a self check and if I take it out on the lake right after, the power valve system and servo works great, everything opens up as it should, i see the ski increase in power etc. If I turn the jet ski off, most of the time the servo does not do a self check, sometimes it does... and the servo/powervalves will no longer work, regardless of how many times i start and stop the jet ski. However, if I unplug the servo and plug it back in... boom, it does the initial self check and works great until i turn the ski off... I think i'm losing my mind....

  8. #8
    Did you install a new or used servo motor?

  9. #9
    Used servo motor

  10. #10
    The test procedure is power on the black and red wires, 12v. Jumper between the black and gray, when the jumper is removed, it should cycle.

    Search for the test, its on the forum some place, but thats it in a nut shell. I bet that new motor is bad.

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