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  1. #1
    Budman's Avatar
    Join Date
    Jul 2008

    New to pwc and need help

    I am looking at a 98 yamaha 1200GP. I just about bought it without riding it. I asked the seller if I could ride it for a day and he agreed. When I get over 35 mph it starts hopping. The lake was very calm with no wind or other boats. I tried it over and over. As I accelerate it starts to hop. I asked the owner and he said its supposed to do that. I took his kawasaki 750 out and no hop at all. Smooth all the way to top speed. I watched a lot of pwc that day didn't see any other ones doing this. He thought it had something to do with trim. What ever that is. Is this something that can be fixed? Any help would be great. Also let me know if it sounds like a good deal. Its a 98 yamaha 1200GP, a 94 Kawasaki 750 tourer and a aluminum tigershark trailer for $5500.00. The yamaha looks new very shiney and no scratches. It has 90 hour on the clock. The kaw looks and runs great but there is no hour clock.


  2. #2
    Join Date
    Oct 2006
    we call that tendancy of the GP/R's porpoising, you can fix it by shimming under the back of the ride plate, usaully adding shims or washers in 20-30 thou incriments until it goes away, by dropping the plate down lower with shims it forces the nose of the ski to stay more planted.

    if you do a search for key words porpoising or bounce ( things like that) you will find lots of references on how to shim its plate to keep it under control.

    i took my project ski out yesterday and it runs up into the mid 70's now but with 40 ltrs of fuel on it it did tend to porpoise a little at times and my plate is already angled ...mine seems to be related to how much fuel i am carrying as once it was under half a tank it was smooth as, same as when its a full tank but somewhere in between there it gets jumpy at the front at around 40MPH.

    stock standard GPR's like the 2002's had bad out problems with bounce as well, you could also investigate if you can step the sponsons on a GP, i dont know much about the GP's as I have only ever road and researched GPR's but thats also worth a look because it made a huge difference to my ski's, stepping combined with shimming the plate may be your ticket to a smooth ride.

    kris will know more about this at a guess as he appears to have owed his current GP for quite a long time, maybe he will chime in.

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