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  1. #1
    dannyual777's Avatar
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    Looks like I lost some top speed on my 1997 GP1200

    My GP's original stator shorted out and I lost spark. I recently purchased a used, OEM stator and after installing it, the ski fired up the ran great. That was 9 days ago and today was the first time I actually got the ski on the water.

    After going through the no-wake zone, I opened the ski up to WOT and watched as my Garmin Foretrex 201 climbed past my previous top speed of 57.5 and it peaked at 58.4 mph before noticeably slowing down to about 55! I could feel the ski slow down!

    The water was pretty close to perfect so it didn't surprise me that it hit 58.4 but it's the slow down that has me worried. No matter what I did, I really couldn't break 56.0 mph after that . I tried full nose up trim and neutral trim. No help. I did notice the ski seemed to want to pull to the right a little bit. At other times, it felt like the aft end of the ski was getting a little squirrelly. Not always, though. The engine seemed to run absolutely perfect. Very responsive! Did I mention that the water was pretty much perfect?

    I brought the back to my lift and checked all three carbs for full, WOT. Checked out good. I pulled the plugs and all three looked good. I looked at the ride plate to make sure all the bolts were in and nothing funny was going on. All good. My original, OEM plastic trim tabs on the bottom of the hull went bad many years ago and I replaced them with the metal ones from George. I think that's who made them. Trim tabs in place along with the 3M 5200 sealer.

    Took it back out and still couldn't get to my previous record of 57.5 much less 58.4 mph. Felt like it was pulling some to the right but it could have been the wind . Rear end got squirrelly a time or two as well. I don't know what's causing that. Top speed, a disappointing 56.2 mph.

    After I got it back on my lift, I did notice that my sponsons were not even with each other. The right hand sponson was lower on the hull than the left side sponson. I think it's been this way for a while but I tried to even them up.

    I didn't get a chance to retest because some angry yellow jackets living under my dock steps decided to attack me. I got stung 3 times . Next time I take the ski out, I'll use a different GPS just to rule it out. The engine seems to be running perfectly. On the MFD, it's showing 7000rpm. I know that tach isn't very accurate and I have no idea what WOT rpm should be.

    Sorry for the extra long post but I felt it was best to give all of the information.


  2. #2
    youngDUMP's Avatar
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    Did you check your pump to make sure nothing was sucked up and possibly left in to reduce thrust? Just a thought

  3. #3
    youngDUMP's Avatar
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    Did you check your pump to rule out nothing was sucked up and possibly left in to reduce thrust?

  4. #4
    Yamaha artisan Cutlass's Avatar
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    Looks like I lost some top speed on my 1997 GP1200

    Even though the engine seems to run perfect and you think its hull or pump related, Id still recommend a compression test just to rule that out.

  5. #5
    dannyual777's Avatar
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    Quote Originally Posted by youngDUMP View Post
    Did you check your pump to rule out nothing was sucked up and possibly left in to reduce thrust?
    The ski is on my lift so I can't see under it. Later today, I'll lower the lift and see if I can tilt the ski on it's side and then raise the lift. I'll have to be very careful to not mess up the ski. I'll give it a try. Hopefully it's possible so I can have a look inside the intake of the pump.

  6. #6
    dannyual777's Avatar
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    Quote Originally Posted by Cutlass View Post
    Even though the engine seems to run perfect and you think it’s hull or pump related, I’d still recommend a compression test just to rule that out.
    I'll do this as well.

  7. #7
    dannyual777's Avatar
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    I was able to lower the lift into the water and roll the ski on it's side at about a 45 degree angle. I then raised the lift out of the water and I was able to get a good look inside the pump tunnel. All looked good with nothing but a clean impeller in there.

    I ran a compression check with all three plugs out and the engine cold. Well, 91 degrees of Houston cold! My USA made compression gauge is 30+ years old and it read every cylinder at 110 psi. Sounds kinda low but every cylinder was within 1psi of 110.

    I did notice that some of the intake bolts were a little loose so I tightened them up. I also noticed that the ride plate bolts were a little loose as well. I tightened those, too.

    I'll try to get the ski back out on the water tomorrow for another test using a different gps.

    Does anyone have any suggestions on the adjustable sponsons? Where should they be set?

  8. #8
    dannyual777's Avatar
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    Got the ski out on the water this afternoon. I used two Garmin wrist mounted GPS units just to be sure. Water wasn't very good today because there were other boats out on the lake. I couldn't even hit 56 mph today. Both GPSs said 55.7 mph.

    Does anyone have any advice on adjusting the sponsons. I got this ski from my brother about 8 or 9 years ago. He bought it new. Originally, one of the sponsons was set lower than the other. Yesterday, I set them both even and it seems to have made handling a little worse. I think I'm going to put the sponsons back the way they were.

    One other thing, as I came out of the no-wake zone and hit the throttle, the engine bogged and died. It restarted immediately but it bogged and died again. The third time I feathered the throttle and it took off. I'm thinking that it's time to pull the carbs and clean them out. Gotta love ethanol gas. NOT!

  9. #9
    MSX 150 guy lives on Mr. GP1800's Avatar
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    When is the last time the carbs were cleaned or rebuilt?

    Is is there any chance that changing the stator changes ignition timing?

    Hope you you didn’t hurt a cylinder or cylinders because of bad fuel

  10. #10
    dannyual777's Avatar
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    Quote Originally Posted by Mr. GP1800 View Post
    When is the last time the carbs were cleaned or rebuilt?

    Is is there any chance that changing the stator changes ignition timing?

    Hope you you didn’t hurt a cylinder or cylinders because of bad fuel
    I tore the carbs down and cleaned them at the beginning of last summer, 2017.

    I don't know anything about the stator and timing changes. Can anyone shed some light on this?

    My compression check yesterday showed all cylinders at 110 psi. All within about 1 psi of each other.

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