Help with old sled motor? | GTAMotorcycle.com

Help with old sled motor?

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timtune

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There's a bunch of clever people here I think you can help.
Buddy's old 340cc fan cooled kawi sled only runs on one cylinder. One carb with a Y pipe so I assume both sides get the same fuel. Swapped the coil leads and no change. Both side have decent compression. The only answer I can come up with is a bad crank seal on that side. There is likely a web in the case that supports the crank in the middle separating the cases into two separate halves and if one seal was bad enough it would be to lean to fire?

Thoughts?
 
timtune said:
There's a bunch of clever people here I think you can help.
Buddy's old 340cc fan cooled kawi sled only runs on one cylinder. One carb with a Y pipe so I assume both sides get the same fuel. Swapped the coil leads and no change. Both side have decent compression. The only answer I can come up with is a bad crank seal on that side. There is likely a web in the case that supports the crank in the middle separating the cases into two separate halves and if one seal was bad enough it would be to lean to fire?

Thoughts?
Click to expand...
Does it catch when revved up?

Sent from the future
 
I'd have to check.
 
You swapped the coil leads but did you swap the plugs? I am assuming pistons are 180 out and both fire every 180?

Mixture should be similar on both sides but not always. I assume choke doesn't help you? Have you let it warm on on the good lung to see if a warm engine behaves differently?

Have you tried a leak down test? A bit more work on a two stroke but easier than getting to the centre of the cases to check the seal.
 
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Been a while since I did those motors, but I’d bet crank seals.

Fuel, fire and compression. You have fuel, fire and top end compression.

Spray some pb or wd around the dead cylinder crank seal when it’s running, if it catches you know the seals are done.

Here’s how you get to the seals:

Crank seals for Dummys

Crank seals for Dummys
kawasakitrax.com
 
If you suspect crank seals don’t rev it up long or the super leaned mixture will eat a piston . Swap plugs and wires , and work backwards . Kawi hasn’t made a sled in a Long time , my guess would be crank seals also , they must be 30? Yrs old ?


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The guys at Winners Circle in Markham are a cornucopia of knowledge for old sled parts (among other things). There are service manuals out there, but I'm sure you'll have to do some digging to find one.
 
Thanks. I was thinking of blasting the the unlit propane torch at the "bad" seal to try and bring it life.
 
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