951 issues

[jborr8]

A little back story. I bought a 2001 gtx carb 951 a few months ago 175hrs. Got it home and noticed some surface rust on the pistons when looking through the rave valves. Decided to investigate. Pulled the entire exhaust out, head,cylinders, and carbs. Carbs were re-built with genuine Mikuni kits. All fuel lines replaced, rave valves cleaned, 3/32 oil injection lines replaced, fuel selector valve cleaned. I put everything back together with WSM gaskets and checked compression 120psi both cylinders. Every time I start the ski on the trailer it wants to instantly run away. I can hit the stop putting or pull the lanyard to stop it. It did run away on the trailer once before I tore into everything but seems to be worse now. I read on here that runaway is common on these engines so I decided to take it to the lake and see how it performed. It was slowly decreasing rpm and eventually stalling at idle, I had to constantly feather the throttle to keep it running. But once I gave it gas it took off high speed ran great no hesitation at all. In the water idle speed seems too low but on the trailer it wants to take off. What could this be?

 

[mikidymac]

Is your throttle cable adjusted correctly.
You should have some slack at idle.

 

[jborr8]

Yes the cable has some slack and I can see that the plate swings fully back to the adjustment screw

 

[mikidymac]

You might have an air leak.

Carb base Gaskets are a common place.

Did you do a leak down test on the engine when you got it back together?

 

[jborr8]

No I tried to make sense of the leak down test but seems too complicated and I’m not sure I own the equipment. Is there any other way to check for leaks?

 

[mikidymac]

Nope and you need to check every engine that comes apart. Without knowing if you have an air leak you will be chasing your tail all summer.

 

[jborr8]

Okay I will try to put together a leak down test. I just pulled the raves to have a look and the piston wash looks good and the spark plugs are nice and brown. Not really showing any signs of running lean. Could this mean it’s more likely to be at the carb?

 

[Jaiello]

I had a similar issue with my xp 951. Rebuilt the carbs and took it out couldnt get it tonidle right. It would rev out. After pulling the carbs out I noticed that the screws on the carbs where loose. They where getting air in. After I tightened all the screws and put it all back together it worked fine. I also had an issue with a new throttle cable which I bought from sbt junk too short. Returned it bought the right one from wsm now I can adjust. Check all the screws on the carbs after you open them to rebuild the screws loosen because of the vibrations. Blue lock tite them back. It’s worth a check