# Ski doo 340 backfiring, now no spark



## shopteacher (Dec 9, 2004)

I have an older skidoo with a 340, I was riding it cold, didn't let it warm up. All of a sudden, she starts backfiring and running crappy (poopy, bad, sucky, terrible) 
She eventually stalls and now has no spark. I tried a new plug to verify it wasn't the plug. Still now spark.
What do you think? Coil? That's the only thing I can think of.
Help me before I make it into a planter. Its right in the front yard.
By the way, It is a 1984 with 5000 miles. Last year it ran relly good.


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## bbnissan (Nov 7, 2004)

I don't know much about the Skidoos, but it sounds sort of like a sheared flywheel key. That would explain why it started running really crappy (the engine was getting out of time) and why it now has no spark (because the crank is free spinning in the flywheel). Just a thought....


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## scrench (Dec 8, 2004)

i would eliminate all kill switches and make sure none are causing the problem , for sure check the one that clips to you, i dont think it is the fly wheel key ,,, but it might be the brain box but if you eliminate all kill switches you can start on the other stuff , i would find the main kill wire on the engine and take it loose there then see if you get spark ,,,,, also some of the cheap spark testers will fool ya


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## scrench (Dec 8, 2004)

could have jumped time i guess


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## shopteacher (Dec 9, 2004)

Thanks I will check the flywheel. As far as safety switches, I don't think somethng that old has them. If the key is sheared, are there other problems that can spring up from that?
Thanks


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## roperdude91 (Nov 10, 2004)

you ran it cold without warming it up, in a car, that would screw up the timing belt, in a small engine, you would shear the fly key


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## bugman (Aug 12, 2004)

yeah before putting strain on a small engine like that before you warm it up it could screw the key up.


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## roperdude91 (Nov 10, 2004)

before putting a strain on any engine with some sort of key or timing belt ya need to let it warm up, i fezxed the timing chain on my mom's van from here just goin tryin to get out of the driveway


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## bugman (Aug 12, 2004)

yeah with an old pushrod chain timing belt, well they can take it sometimes but let em warm up. unless you keep a block heater on it or an oil heater


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