97 XP Starting/poor compression

[darrylgood]

Hello All,

I have bought this ski at the starting of the season, ran it perfect for 2 weekends. It ran great and then started to bogg down a bit like it wasn't getting fuel. We then found out it was an ignition problem. (I haven't flipped it or anything like that) Thought it was the ignition coil, but that was fine. Then did a compression test. One cylinder was good the other was like 20! Why would this all of the sudden happen? Is my ski useless now? Any ideas on where to look first?

Thanks so much everyone!

 

[Chris488994]

Was it the rear (PTO) cylinder with low compression?

 

[darrylgood]

Yes it was the rear, Actually is was 20 pounds

What are you thinking?

Thanks Again

 

[kustomkarl]

Pull the heads and have a look inside. It may have seized up on you from a low oil condition or overheat. Low compression means trouble inside the engine. I'll give you some added info on doing a compression test just to be sure you did it correctly.


The compression gage, will screw in the cylinder head in place of the spark plugs. To test compression, remove the spark plugs. Place spark plug caps on the plug cap studs near the cylinder head to ground the empty caps. This completes the circuit of the ignition electrical system and prevents any electrical problems from the caps being un grounded. Using the correct adapter for the threaded end of the tester,( same length of the spark plug threads length)screw in the tester in one plug hole. Hold the throttle wide open. Push the start button. Watch the compression gauge, when it peaks out at the most compression, let go the start button. Read the psi number. I would do it 3 times to be sure it is accurate. Check all the cylinders the same way. The ideal compression is 150 psi per cylinder. If it is less, it's not a problem as long as they are close to being the same. If the psi is less than 90 it might need be time for a tear down and a rebuild. If the psi in 1 cylinder is say 140 psi and the other is 80 psi you need to tear down and repair. This difference is a lot then there is a problem. The ratio of difference is 10% difference between cylinder readings. I hope this helps you.

Karl

 

[Chris488994]

When was the last time your carbs were rebuilt?

It is common for the the little filters in the carbs to get clogged with a green goo from the gray Tempo fuel lines breaking down.

Usually the rear carb filter clogs first letting it run lean and burn up one cylinder.

Or could be the possibility that your oil system wasn't working right.

First thing I would do is take off the head so you can see the top of the piston and cylinder wall. You will see the problem then.

Rebuild the top end both cylinders, buy the upgraded pistons with the coated piston skirt, rebuild the carbs, change the fuel lines, clean or change the fuel selector valve, do not turn the valve dry use some kind of lube, clean fuel filter and look into premixing your fuel and what to do with the oil pump. You still need the pump and oil tank.

That way if your engine is running then you know you are getting oil.

The ski should run like new.

Good luck buddy. Let us know what find out.

 

[darrylgood]

Thanks guys,

Chris488994,

When i take open up the cylinders to see the piston head and walls, what am I looking for? Scoring on the walls? Where can i order new pistons from online if thats the issue?

Another thing I just remembered is that when I first got the ski, it had been sitting for a while and there was oil in the bottom of the hull. It must be leaking some where or a seal is cracked/old.

Do you think the oil issue tells us something?

Thanks!