98 GTX Limited 951 not starting

[armandjonker]

Hey guys, i'm new here on the group and actually got my first ski yesterday. I got it at a really good price but its not starting or running. the motor turns but it doesn't start. Today I started some trouble shooting but i'm not very familiar with 2-stroke engines. I started by checking for continuity on the spark plugs and found that both plugs were bad. I replaced them and checked whether there is spark on the leads which there is. The previous owner tried cleaning the carbs with carb cleaner and spraying it into the carb after which it died. My suspicion is the he has blocked the jets as this ski is filthy inside the hull. What else can I check for?

 

[tobytd]

First thing to do is take a compression test. Auto parts stores ‘ rent ‘ testers.Your 951 engine should be 130 if perfect

 

[mikidymac]

I would agree, compression test before anything.

Also running carb cleaner in a 2-stroke can be a kiss of death since it removes all the lubricating oil from the engine parts.

 

[armandjonker]

I managed to get it started for a second or two, when I went over the workshop manual I noticed that it only showed 1 fuel filter and in my ski there was an In-line filter installed as well, but it was empty. So now I want to run new fuel lines and then I saw that on the fuel selector switch (RES - ON - OFF) that one of the lines was not connected. can anyone perhaps help me with the selector diagram going to the tank and carbs, or if you can just make a small sketch I would really appreciate it

 

[armandjonker]

Thanks for the advice, I will do a compression test in the morning

 

[mikidymac]

You don't need a second filter, just the factory strainer and the tiny ones in the carbs.

I can't say it enough on these, clean the fuel strainer and a new o-ring on it, Replace the fuel selector and rebuild the carbs with only genuine Mikuni parts or you will destroy the engine.

Alos you have to run API-TC full synthetic oil.

Don't spend a dime until you check compression.

From the fuel sender the ON and RES run to the ON ans RES fittings on the selector then the middle fitting on the selector goes to the fuel strainer then from the strainer to the carb.

 

[armandjonker]

Noted, thank you very much for the advice. This is by far the best forum I have ever been on!!

 

[armandjonker]

So I couldn't get a compression tester, and decided to check if I could see any damage on the pistons through the rave valve opening, it wasn't a pretty sight. If I decide to go oversize on the sleeves and pistons, would I need to change the jets to a larger jet or will the std one work. I'm going to do a full motor rebuild.

 

[mikidymac]

Yes, that's bad!
Full rebuild including crank, balancer, reeds and don't forget to rebuild the carbs and fuel system.
You don't need to rejet the carbs for oversize pistons but you should have the shop also trim the RAVE valves to clear the new pistons. I suggest Group K for cylinder machining.

 

[Rabid]

What caused that issue with the pistons?

 

[mikidymac]

Can’t say for sure but in my experience 9 out of 10 times it’s dirty carbs.

 

[armandjonker]

I suspect when the previous owner was trying to clean the carbs by spraying carb cleaner into the running motor, there was no lubrication from the 2 stroke oil as you also mentioned @mikidymac

 

[mikidymac]

I suspect when the previous owner was trying to clean the carbs by spraying carb cleaner into the running motor, there was no lubrication from the 2 stroke oil as you also mentioned @mikidymac

That would be correct. Carb cleaner down the intake does absolutely nothing for the carbs.