Oh dang, what just happened

[7ford7]

I'll start from the top, got off work today came home hopped on the ski. Went on business as usual, rode for about 45min. Pulled the ski, went to start it to clear the waterbox, started it and rev'd it once, twice, and on the third time it stuck, wide effin open. I did what I do best, panic. Hit the stop switch, nothing, pulled the kill switch, nothing, now I really panic, as quick as I can, pull the hood, and pull the plug wires, still nothing! All logic is gone now, so I pull the battery cables and as I'm looking for the next thing to tear apart, it slowly revs down to die. I'm at a complete loss, I haven't even put the carnage back together, I need to know what happened, and what to do to fix it. The ski is a 785 sn sj with dual mukini 44s and bpipe and more. any help is greatly appreciated, and even if you live near eddy ville, by. I would be willing to bring the ski to you to have a look. Thank you.

 

[OCD Solutions]

air leak, there i got it in before everyone else, lol.

 

[7ford7]

Wow, air leak, that sounds way to simple for the fear that just went through me lol, so air leak. What do I do now?

 

[JustinB]

What do I do now?

Find air leak; fix air leak

 

[7ford7]

Pehaps I should add some more info, I'm a complete amature when it comes to skis, I have plenty of expirence in motor work, just not with skis. Now I'm not asking where the air leak is, but where to look and how to find it.

 

[Sanoman]

Get a kit from watcon that you can do leak down test!

 

[Matt_E]

The slowly revving down and dying part would worry me quite a bit.
Do a compression test.

Next time this happens, push and hold the stop button and pull the throttle wide open. That'll kill it.

 

[NVJAY775]

I forgot to tighten my carbs down last year and it did it before I got it in the water:buttkick:

 

[Patrick Star]

Dude, an out of control engine will traumatize you. I had a run away engine just like this a yew years ago and now I when I start anything that event is in the back of my mind. Can't help it. I bought this old airhead that had not been started for a few years and when the time came to crank it... I was like hope it doesn't peg out like that. Sounds dumb but dam, it's crazy when it happens.

 

[Powerhouse]

I have a modified CDI, and it will do that whenever it wants. If you grab the throttle while its going all out uncontrollable rev, and then release again, and press the kill switch, it works for me

 

[Matt_E]

A CDI has nothing to do with that condition.

 

[crossr]

Usually the leak is somewhere on the intake side of things. Could be a loose carb or blown gasket or even a cracked intake manifold. The easiest thing to do is pull the choke if you have one or start pumping the primer. Hitting the stop botton never worked for me or pulling the plug wires. I've only had kawi's though. It does make you crap your pants the first time it happens.

 

[Matt_E]

Note I said pushing stop AND holding the throttle wide open. :bigok:
That kills the spark while flooding the engine with full air/fuel which cools the plugs to where they don't glow

 

[badboyr6]

did you do a comp test?

 

[baxt3r]

Would it help if you cut the fuel off too? Or would it take too long to drain the fuel lines for that to be effective?

 

[ger87410]

Would it help if you cut the fuel off too? Or would it take too long to drain the fuel lines for that to be effective?

Don't do that!!!!

Fuel will spray everywhere.

 

[superwetbrett]

Would it help if you cut the fuel off too? Or would it take too long to drain the fuel lines for that to be effective?

its reving because its lean not because to much fuel

 

[SJBrit]

Just to be clear, a lean motor runs hot, and a super lean motor (like one with an air leak) runs super hot. In that condition it's basically a diesel motor - the high pressure and heat alone will cause ignition, no need for a spark at all. That's why it runs away - it's a vicious cycle with the motor getting hotter and hotter until it either rips apart or (I hate to say it) has a hot seizure characterized by, ahem, slowly revving down and dying.

The only way to stop a dieseling motor is to cool it down which means getting a very rich mixture in there - lots of fuel and little air. First thing is wide open throttle - that's lots of fuel. If you have a primer then crank that sucker - more fuel! If you have a choke then close it - that's less air. If you don't have a chole then hold your hand over the flame arrestor to act like a choke.

Like Matt said, you should definitely be worried about what damage was done screaming wide open like that, especially since it stopped itself.

 

[Sidsol]

one of my old skis did this,, i just quickly covered the carbs and choked the bitch out

 

[7ford7]

Well I'm clearly in over my head, i know i cant be the only person in the lakes area of KY that rides, is there anybody that can help? I'm not looking to have it fixed by someone, but have some instruction. As of now my options are fairly open.