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Discussion Starter #1
Hello,

Recently picked up a fairly new (outside) 2004 Yamaha SUV1200 local.
Get it out on the water the first time, with 3 ppl on board, it cavitation really bad which top at 5mph which I quit that day and return on the following day.

The next day only 2 ppl(210lb +140lb) on board, rarely cavitation which the top speed at really smooth bay sea water at 45-50mph GPS speed, the reading on the dash is about 40mph when full throttle. The rpm when at full throttle was about 6800-7000 rpm. And it get on plane pretty fast about 2 sec on plane.

The ski have 125hrs on it, the previouse owner was a old lawyer which he said he never replace the impeller/wear ring and always get it service by the dealer.

Ive heard that SUV sometimes like to have cavitation which I ordered R&D intake grate and pump seal kit to try if any improvement.

I bought a harbor freight tools's compression tester to test the 3 cylinder, 3 of them are the same at 90 psi, which if it possible to be faulty compression tester or it is really that low?

Btw, i calculated that day it consumes 7.8Gal of fuel for 2 hrs and total 25mi traveled, mostly when full speed.

Not sure what I suppose to do next to fix the cavitation besides the intake grate and pump seal, will see how it perform after installing it. I read other site about top speed on a Yamaha SUV, somebody says 50mpg somebody says 60mph, but I dont know how many ppl on board the speed they are talking about.

And I noticed the trim cable was frozen, was that a easy job to fix or need to take to dealer?

Thanks!
 

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Hello,

Recently picked up a fairly new (outside) 2004 Yamaha SUV1200 local.
Get it out on the water the first time, with 3 ppl on board, it cavitation really bad which top at 5mph which I quit that day and return on the following day.

The next day only 2 ppl(210lb +140lb) on board, rarely cavitation which the top speed at really smooth bay sea water at 45-50mph GPS speed, the reading on the dash is about 40mph when full throttle. The rpm when at full throttle was about 6800-7000 rpm. And it get on plane pretty fast about 2 sec on plane.

The ski have 125hrs on it, the previouse owner was a old lawyer which he said he never replace the impeller/wear ring and always get it service by the dealer.

Ive heard that SUV sometimes like to have cavitation which I ordered R&D intake grate and pump seal kit to try if any improvement.

I bought a harbor freight tools's compression tester to test the 3 cylinder, 3 of them are the same at 90 psi, which if it possible to be faulty compression tester or it is really that low?

Btw, i calculated that day it consumes 7.8Gal of fuel for 2 hrs and total 25mi traveled, mostly when full speed.

Not sure what I suppose to do next to fix the cavitation besides the intake grate and pump seal, will see how it perform after installing it. I read other site about top speed on a Yamaha SUV, somebody says 50mpg somebody says 60mph, but I dont know how many ppl on board the speed they are talking about.

And I noticed the trim cable was frozen, was that a easy job to fix or need to take to dealer?

Thanks!
With the intake and seal kit you may very well solve your cavitation problems. Once you have the intake and pump shoe off measure the Impeller to wear ring clearance it should be below .018" if it's close to or over that then a new Impeller will be needed in the near future.

When you install the seal kit glue the pieces in with some good silicone caulk. Just a little will do it. Then seal the shoe with silicone as the pic indicates in green. You don't want air to be drawn in around the shoe.
Top speed on the SUV I believe is around 55+-. Single rider.

If all is sealed tight and your pump clearance is good you should be able to take off full throttle with no cavitation all the way up to reaching top speed.
 

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Discussion Starter #3
Hello,
thanks for your reply.
As well, what do you think about that compression reading?
For the speed part, im not so sure about the 50mph reading which when the speedometer read on the ski says 30mph, i read the gps speed from phone says 38mph, but when the speed on the ski says 40mph(top reading), it was so fast that Im not able to hold my phone that I estimate that gps reading should be 45-50mph.(Going to install a GPS kit on the ski) And the low compression reading on my engine, for 90psi for all 3 cylinder, is it most likely a faulty tester? What will happened if a engine really have a that low compression perform? Thanks!
 

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As for compression the good thing is there all even. But I think your guage is reading low. I have one from harbor freigh
t and it's way off.
Other thing is also did you hold the throttle full open while testing? I use a wire tie to hold it right back to the handle bar. This will affect outcome drastically.
Try borrowing a tester from AutoZone or whomever you have there. Most rent tools now days
 

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Your compression numbers should be up in 125/130 range (new). At 90 you would really be having runnability issues. That's why I believe that guage is off. With 125hrs on it your probably around 110/115 for normal wear. Provided there's no issues. Of coarse this is all subject to use and abuse. Otherwise known as just an educated guess.
 

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Discussion Starter #6
Hello Dave in DE.
Just installed the GPS retrofit unit on the ski and i get the top speed reading on the dash with 2 ppl on board on not calm water was 42-43mph, not the 50mph i imagine.
And it probably be a bad tester, i will get a another one to test again. and about the full throttle part, how much different it will be, as I test the compression with no throttle?
Thanks
 

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What was your Impeller to wear ring clearance? Did you measure it while sealing the shoe?

I wouldn't bother with another harbor freight compression guage. Every one of there units I've tested is no good. Not accurate. As I said rent one from AutoZone or napa exc..... Whoever is near you. Most all auto stores rent tools now.

Not holding the throttle open while doing a compression test will skew your out come dramatically. No way to say how much. That would very again based on motor condition. But you need the throttle open so it can take in as much air as possible.
 
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