Thread: My first yamaha gp1200
05-08-2010, 06:29 PM #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!
05-10-2010, 11:47 AM #2
- Join Date
- Nov 2009
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.
05-10-2010, 12:37 PM #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..
05-10-2010, 01:07 PM #4
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.
05-10-2010, 01:08 PM #5
And Pete.... Did you use genuine Yamaha crank seals?
05-10-2010, 02:49 PM #6
05-11-2010, 09:32 AM #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.
05-11-2010, 09:41 AM #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!
05-11-2010, 10:25 AM #9
Thats a just a possibility of an explanation of the speed difference. Not sure how much of a chop you're actually dealing with.
05-11-2010, 01:21 PM #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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