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Discussion Starter #1
well heres the scoop, i have a 340 engine with a single carb feeding both cylinders. Both cylinders have good compression and are about 5-10 psi apart from one another. The pto cylinder keeps fouling out and the other cylinder is running fine. We changed points and condensors with no change. And the timing is right where it is supposed to be. Also the advance mechanism is working correctly...any ideas?????
 

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Stupid question, but is the gap set right? I had a poorly gapped plug in my sled and it would foul very quickly. Im sure you've changed them though. Oh well, im out of advice. Sorry

95 XLT Special
88 Saffari 377
89 Saffari Saga 377
 

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Have you checked the seal on the pto side? If it leaks you lose the crackcase preasure and you lose the charge to the cylinder.

 

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Discussion Starter #4
I'm not losing the charge...im getting too much charge...the plug is running way too rich. If it were the seal wouldnt that cylinder be running lean?
 

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If they don't fire, they get wet. Spray some starting fluid around the pto seal when it is running. If it speeds up, then the seal is leaking. I dunno, just trying to help.

 

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Have you checked the spark with a spark tester, you may have a poor wire causing a weak spark, how about testing the resesitance of the sparkplug boots if equipped with resistor type boots. I had a sled I had to run 1 step hotter plug than called for by the mfgr.
Give up an update.

we're not lost, we just misplaced ourselves.
 

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Maybe check the coils. Switch the two of them around and see if the misfire goes to the other cylinder. Bad coils = bad spark.

 

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Discussion Starter #8
wires and boots are new...but i think im going to try what erick said and switch the coils around...that seems like the easiest thing to try next. I'll keep ya posted, although wont really be able to test it out till we get some snow.
 

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I agree with Erick's suggestion, switch the coils around, then see where you are at. If that switches the fouling plug, then switch the cables. You'll isolate the problem somehow. Have you tried running hotter plugs? It might help.

95 XLT Special
88 Saffari 377
89 Saffari Saga 377
 

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Discussion Starter #10
Yeah i tried running hotter plugs...went up one step..still fouled them out...went another and fouled again...didnt try to go any hotter than that.
 

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Does it have reeds in it ? I had a old sled that did that once and it was a chunck of wheat got in there and was holding the reed open....just a thought..
 

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Are they fouling from oil or gas? If it's gas it will evaporate from the plug if its oily/ashy, then perhaps your oil injector(if you still run one) is out of adjustment??

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