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Discussion Starter #1
Hey guys. I have got a 02 xlt 1200 and a 02 gp1200r. I have had them for a year now and they both have about 108 hours on them. They were in the shop about a month ago and they checked compression and all looked good. My question is, the gp1200r is slower then the xlt1200 up till about 60 then it will pass it. It mainly gets pulled on the launch and then plays catch up. it is fast then the xlt1200 in the top end, its speedometer says "68mph" while the xlt tops out about "57mph".. today i raced a 04 red stroke yamaha, not sure what size it was but, he pulled me harder at the beggining and i SLLOWLY played catch to finally pass him around 67. He knew more about waverunners than me and said that i should have beat him much worse and that i may need a new impeller?
 

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Yeah, does the ski have cavitation??? If so, seal the pump shoe up and get a 13/19 impeller. To improve the speed of the GPR even more without breaking the budget, install a RIVA ride plate. Good for about 2-3MPH.
 

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Might have some issues with your jet pump but sounds like maybe carbs. Compression good, so what about spark? Time for the carbs to be rebuilt with fresh fuel also? Don't forget fuel pumps.
 

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Discussion Starter #4
Thanks for the quick reply guys , and truthfully I do not know much about jetskis I am more of a car guy.. What is cavitation?? And is rebuilding the carbs a very expensive job?? It does not bother me that much since I feel like the ski is fast but knowing it isn't running it's full potential Is kinda annoying
 

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poping noise

Let me ask you because it sounds like you have a similar machine.

I road a jet ski for the first time today. I would like to buy this ski.
"2000 Yamaha GP 1200r Wave Runner with trailer
Less than 80 hours (79.1)"

It had a slight pop, like a misfire at speeds less than 25 miles per hour. From 25 to 60 it was smooth. Is this normal? The seller seemed to think so.
Also, two nuts on the exhaust manifold were finger loose.
 

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Mcgahanfl, the pop is normal. Just make sure you give it a good once over when you get it (check all bolts etc). Trey1010. Cavitation is like a slipping clutch on a car. Heaps of revs but slow response. If it is cavitation, do what I said in the last post. If the engine is slow to react or bogging down, it will be the carbs. The carbs on a Yam 1200 p/v motor would be hard to do for a first timer. If it sound like carbs to you, let us know and we can tell you how to do it. But, by the description you have given about its performance, I would think the problems in the pump unit. Pretty standard issue on a Yamaha.
 

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Discussion Starter #7
It's hard for me to tell what it is but when it first starts for the day it will die till it fully heats up!! Does it seem like a car problem ?? Thanks again
 

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Discussion Starter #8
It's hard for me to tell what it is but when it first starts for the day it will die till it fully heats up!! Does it seem like a carb problem ?? Thanks again
 

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Forgot about the exhaust valves. Posseible issue there, but you are reaching top speed right? Usually power valves cut down the top speed.
 

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When the ski starts from cold or after it has been run and then sitting for 10minuits, it will have low fuel pressure which means when you go to accelerate it will die until it builds fuel pressure up. If it does this all the time it will have a carb problem. If the engine revs up and hits the limiter when the engine is warm, and the ski is slow to respond, it has cavitation. Just like a slipping clutch (big revs-slow take off).
 

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Discussion Starter #12 (Edited)
Okay. It does not seem like cavitation to me at all, and it only dies when it is cold and has yet to build fuel pressure, so next thing may be the jet pump? And yes It reaches top speed, I believe 68 is top speed, maybe if I get a video next time I am out that will help determine the problem, it feels like at about 10-15 mph it gets into it's powerband and then pulls great
 

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Mate, you are getting very confused here. You said you don't think it is cavitation but then you said the next thing maybe to look at jet pump. NO NO NO. Refer to my last post. When it is warm and you go to accelerate, does the engine rev heaps and the ski slow to react (just like a slipping clutch)???? OR, when the ski is warm, and you go to accelerate, does the engine bog down and almost cut out (just like you let the clutch out too quickly on a car)????. Top speed is irrelevant, with both problems it will still reach top speed.
 

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Discussion Starter #14
ok LOL I amsorry.. Okay It does more of a bogging thing when I floor it off the line, not really like a clutch slipping at all.
 

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Ok cool. Well the carbs will have to come off and be cleaned out. The low jets should be all 92.5 and the high jets should be 135. The mixture screw settings should be LOW= #1:
1&1/2 #2: 1&1/2 #3: 1&3/4 HIGH= #1: 5/8 #2: 5/8 #3: 1. You can give them all a bit more if you want if the engine has done a few hours. Its not the easiest job for a first timer. Are you sure you want to do it?
 

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Discussion Starter #16
LOL no I am not, but I don't have much money to throw at them... How much would a job like this cost??
 

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In Australia, something like that would be around $400 to $500. Usually you wouldn't need a carby kit per carb however each carb may need a gasket/diaphram or check valve here and there.
 

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Discussion Starter #18
Hey guys I went to the track for along time yesterday and I realized that it really does feel as if a clutch is slipping off the line, so it may be cavitation? What's the fix for this??
 

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Check the impeller and liner gap. Should be under 1mm. Check the impeller for any damage. Check the intake grate for any blockages. And if all this is fine, remove the pump shoe, clean it and sikaflex it on all the surfaces that connect to the ski. Including underneath the pump ring where there should be a black seal. Remove that seal before you seal it obviously. The pump shoe is the thing right underneath the ski that directs water to the impeller. It has 4 x 12mm bolts. And you will have to remove the intake grate before you remove the pump shoe.
 
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