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  1. #1

    My first yamaha gp1200

    I picked up my 97 gp 1200(about a month and a half ago) and it was supposedly in perfect condition, I did a compression check(125 across) and I test drove it, everything was great until about the 5th time out when I started having performance issues with the ski bogging down. I found out it was the carbs and rebuilt them with mikuni kits, it ran much better and I gpsd it at 56.6 mph with one person and a half tank. I then played with the ride plate adjusting it up and down with washers in the front, first I added too many, but still got 57.5 but the ski kept bouncing, I removed two of the four washers and this got me to 58.0 on the gps(still with some slight annoying bouncing). while running it hard one day it died on me, would crank but not fire. found out later I had lost spark from a sliced wire in my stator, I soldered the wires back together. Upon inspection we realized the main engine seals were almost gone. I tore the whole motor down(60 hour sbt rebuild), replaced the main seals, this time sealing them in good, and put it back together. I adjusted the carbs, took one more washer out of the front of the ride plate and my numbers today (with my girl on the back) was 60.6 gps, it also takes off like a rocket with no hesitation and never bogs down(also no more bouncing even across very choppy water!), I ran it extremely hard today for three hours with out one problem.I plan on filling the intake grate/ rideplate boltholes as well as seal the shoe soon to maybe get a couple more mph So overall I have spent $2850 including the ski, trailer,cover, and all repairs(which have all been done right). well worth it it my book, long live Yamaha!


  2. #2

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    Wait, you put washers at the front of the ride plate?
    I've heard many put washers in back but never the front.
    Trying to smooth out my 97 GP760 with a Pro-Tec intake grate and Riva ride plate (with two washers in back). Water was very choppy first time out so I couldn't tell if it made a difference or not.

  3. #3
    well Im not a pro so there is prob better people to ask, but from what Ive learned searching the forum is you want the front of the rideplate to be as flush with the end of the intake grate as possible, but NOT hanging past(below) the intake grate, I found that when perfectly flush it had my ski bouncing slightly so I removed one more washer and I still had to leave a slight dropdown from the intake grate to the rideplate to get the best top speed and handling characteristics. I heard shimming the rear of the plate brings the nose of the waverunner down therefore causing more friction and resulting in less speed.. just my two cents I could be wrong but I did get decent speed/ handling gains with the way I did it..

  4. #4
    Here come the smokers! OBXJeepGuy's Avatar
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    The GP1200, and the GP760 are tow different beasts. With the 1200 you have slightly more forward weight which will help with the porpoising. I finally got rid of the porpoising in mine... SO frigging annoying.

  5. #5
    Here come the smokers! OBXJeepGuy's Avatar
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    And Pete.... Did you use genuine Yamaha crank seals?

  6. #6
    bullisland's Avatar
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    Quote Originally Posted by toyterrific View Post
    Wait, you put washers at the front of the ride plate?
    I've heard many put washers in back but never the front.
    Trying to smooth out my 97 GP760 with a Pro-Tec intake grate and Riva ride plate (with two washers in back). Water was very choppy first time out so I couldn't tell if it made a difference or not.
    I believe rossnemo said it best:
    Quote Originally Posted by rossnemo View Post
    I have read several posts lately from newer forum members who have modified their skis and are unhappy with its performance. Some have seen a loss on top speed, others claim its a dog out of the hole, etc.
    It is very important to remember that when you mod your ski, try and modify it as a package deal, and not with just 1 or 2 pieces of the package.
    It is this reason that many aftermarket manufacturers sell stage 1-2 and 3 kits.
    Think of it as a sports team.. If you have only 2 good players on a basketball team, the team sucks, and needs 3 other good players to all work together as a team and help one another. This is the same way modifying a ski, or any other toy goes. One modification compliments another.
    Just putting on a 1200 grate and sealing the pump shoe will slow your ski down, it needs the other team members to make it all go.
    Just installing an EFI controller and a d-plate will do nothing for your ski without the other players also.
    Installing a 14/20 prop without creating more power to spin it is a very common mistake seems like, and creates a major dog with a stock engine trying to spin it.
    I know many people modify as their wallet allows them to and cant afford to do the entire ball of wax at once, and i understand that, but just be aware of this fact of life.
    There are many different combinations people use, so STUDY closely what Jerry, R&D and Riva have for sale, and remember their recomendations for packages are that way for a reason.
    Its all in the combination of parts, and how well you pay attention to the small tuning details that determines how fast or slow your ski will be.
    Search this forum also and ask BEFORE you modify if you are not sure which way you are going. There are no stupid questions, and the answers are ALL here on Jerrys forum.
    So STUDY/READ/LOOK AT THE PICTURES on this forum in search mode for hours and hours, before you spend your hard earned dollars and you will avoid the frustration of owning a modified slug.
    You will be glad you did.
    There is an incredible amount of FREE information on this forum and it can take days/weeks to digest it all.

    And last but not least, if your not SURE, and have no experience in that area, then please dont give out poor/misleading advice.

    Proper planning prevents poor performance...
    Sounds like cleche classroom bullshit, but its not. Its oh so very true..
    Its your hard earned money, so spend it wisely and smile when you grab some throttle.
    Thanks,
    Ross



    Quote Originally Posted by pete6053 View Post
    well Im not a pro so there is prob better people to ask, but from what Ive learned searching the forum is you want the front of the rideplate to be as flush with the end of the intake grate as possible, but NOT hanging past(below) the intake grate, I found that when perfectly flush it had my ski bouncing slightly so I removed one more washer and I still had to leave a slight dropdown from the intake grate to the rideplate to get the best top speed and handling characteristics. I heard shimming the rear of the plate brings the nose of the waverunner down therefore causing more friction and resulting in less speed.. just my two cents I could be wrong but I did get decent speed/ handling gains with the way I did it..
    You're on the right track with searching! Its been covered plenty. When it comes down to it, each ski is going to react differently. Just keep playing with it and a note to remember...she is going to ride completely different when you ride solo and 1up (with your girl). So you might have it shimmed just right with her riding also, and then you go out by yourself and its like riding on a trampoline! Just keep playin and wrenchin and enjoyin!

  7. #7
    jeepguy, yeah the porpoising was really frustrating especially when trying to beat another ski and Im jumping out of the water half the time losing tons of speed! But now she runs straight across even moderate chop with no porpoising and just kinda slices through... if it does start to porpoise I turn slightly right or left and it levels out quickly.. and yes I used genuine seals and siliconed them in for extra strength.

  8. #8
    Bull, The ski handles great now with either one or two riders so I feel pretty good about that, but the wierd thing is on that day I could only get 59.4 by myself, and on the same run(very-light side wind, chop/ slight windripple) my girl and I hit 60.6, I thought that was strange, I just told her she must be my good luck charm lol!

  9. #9
    bullisland's Avatar
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    Quote Originally Posted by pete6053 View Post
    Bull, The ski handles great now with either one or two riders so I feel pretty good about that, but the wierd thing is on that day I could only get 59.4 by myself, and on the same run(very-light side wind, chop/ slight windripple) my girl and I hit 60.6, I thought that was strange, I just told her she must be my good luck charm lol!
    Well, it sounds like it might be the fact that with the extra weight, it is just keeping you planted in the water better since you're going through a chop therefore giving you a higher top end. And with only yourself, the ski has less weight keeping it planted in the water, therefore bouncing more, and losing that top end.

    Thats a just a possibility of an explanation of the speed difference. Not sure how much of a chop you're actually dealing with.

  10. #10
    It was a pretty small chop that day, hard to explain, but I guess you could say the chop was around 3-6 inches across the entire waterway. I thought about that too that maybe her extra weight(only 105 lbs) in the back(and we both were very far back on the ski) it was keeping my intake planted in the water therefore not losing thrust. I need to get out on a perfect day with no wind or chop(by myself) to get a true reading I guess, I am hoping for around 61-62 gps with just me, plus I am filling in the intake grate bolt holes and rideplate bolt holes before I test it again!

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