2001 GTX DI (RED)951 Low Compression, Can I just Rebuild Top End or wasting my time

[petes2001seadoo]

I purchased a used 2001 Seadoo GTX DI. Ran great all summer until my last outing. It was running fine and then just stalled out. Replaced the plugs and still no start on the water and will barely run on trailer. The ski has 215 hours on it. I figured it was the fuel pump but I had the 107 psi so fuel pump is good. I then decided to do a compression test on the cylinders. I pulled the plugs and disconnected the wire harness to the fuel injectors and took a compression test. The cylinder closest to the back seat registered only 90 PSI and the other cylinder closest to the key registered only 30 PSI. I threw my little temper tantrum as I was dumb enough to take the guys word for it that the compression was at 140 but I highly doubt it and can't prove it. I'm done with my anger management classes so I need to manup and fix this thing. So, here are my questions and would like to have a detailed answer from experts who have knowledge about these 951 DI engines. I know everything about car engines about the do's and dont's but not about these two strokes.

1) Is the engine trashed and should I just buy a new one?
2) With 215 hours, can I just rebuild the top end and get another 200 hours of use out of it? I don't want to waste my time and money if I do a top end rebuild and it only lasts 10 hours?
3) If most of you agree that doing a top end rebuild is a good idea, can I do the rebuild with the engine inside the ski?

 

[SabrToothSqrl]

Send it to a shop that will give you a no fault warranty, and you'll get another 200 out of it. Or 10-12 years.

A top end will buy you maybe a season.

Also, investigate why the engine failed.

 

[JCJ256]

Agree with finding out what killed this one first. If you ran great all summer then my gut says you probably did have 140 psi, or close to it .... until your last ride. If the engine had been running closer to 100 psi or below all summer, you would have definitely noticed a prominent lack of power. If it ran "great", then more likely your compression was fine, or at least MUCH better, and something must have happened very quickly to cause the loss of compression. Though several possibilities, lack of injection oil (one way or the other) and running with a very lean condition should probably be explored. Either way, if you get a rebuilt engine, or rebuild it yourself, you will undoubtedly reuse all of the supporting parts - injectors, throttle bodies, oil pumps, etc. If any of these are the cause of your current problem, you will be setting yourself up for another quick rebuild later if you don't know what happened to this one.

 

[mikidymac]

Never do just a top end on a 200+ hour 951. All or nothing.

 

[tkarvelis]

What should the compression on a 951 DI be? I am looking at one next week with 130 hours. It has the maintenance light on it.

 

[petes2001seadoo]

the compression should be 140 psi

 

[SabrToothSqrl]

depending on gauge reading, battery, starter age, etc. 120-140 is fine. the test is on the water, with a good jet pump. you want to hit as close to 7,000 RPM as you can.

 

[tkarvelis]

I don't know if I will be able to test on the water since it is in nc, and late November. The lake will be cold, so it will be on the trailer, so I might hit the Rev limiter.

Since it has issues staying running, I don't know how smart it would be too, bc the lake will be empty.

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