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Discussion Starter #21
tried posting video yesterday, not very good at that. new gaskets in exhaust . pull choke open and no help. did spray contact cleaner around manifolds and engine starts to die.so possibly i should replace them and see if difference
 

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Are all 4 plugs the same color?
And are the gaps correct?
These are a twin plug continuous loop circuit and maybe if one is too large or closed it may cause some spark variances.
Not sure if you have 2 pulse generators maybe one is going out of specs when warmed up and disturbing the spark intensity. Your year may be only one.
 

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tried posting video yesterday, not very good at that. new gaskets in exhaust . pull choke open and no help. did spray contact cleaner around manifolds and engine starts to die.so possibly i should replace them and see if difference
I've seen leaking boots manifest themselves as an irregular hunting idle and I've also seen them act like a rev. limiter at higher engine speeds, so while I have not seen the symptoms shown by your bike it is not too much of a stretch to believe it is possible.
I use spray carb cleaner for the test as it is usually sitting on the bench, but the effects of the contact cleaner seem to be pretty much the same and would indicate a leak. With a well sealed intake there is no way it would be sucked in and effect the engine.
Good detective work, it looks like you found a problem let's hope it is THE problem.
 

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So maybe RPM triggered?
I know when I put my Cobra Boulevard Classic Slashcuts on my 750 ACE the rear pipe only had a blonde pubic hair of clearance from the end of the axle.
I "adjusted" it out to give 1/4".
Although likely a different pipe style I wonder if his pipes clearances are that tight too and a certain amount of throttle gives a certain frequency that causes the pipe to hit which would go along with your previous banging suggestion.

As for posting videos there may be a way to do it directly here, but the ones I see are hosted elsewhere and then linked here.
I think this is a big possibility. Try cushioning the exhaust somehow with a potholder or something that won't melt and just see if it works. If that doesn't work. My easy way of checking misfires is connect a timing light to the suspect cylinder lead and watch the light when it gets up to your machine gun sound. Maybe a plug went bad on you causing a misfire.
 

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If you're sure it's only 1 cylinder, Pull the tank and the airbox, fire it up and rev it, watch the slides. I'd suspect the slide for the rear carb is sticking or otherwise having issues. might have gotten a piece of dirt in there when doing the jet kit? They should work equally.

And most of these run lean enough they are always doing a bit of this, mostly when you let off, but you can't hear it through the stock muffler. (there's a reason they call them "mufflers")
Some universal baffles in the pipes may help (and save your hearing, these are stupid-loud with no baffles.) Adding some baffles for a bit of back-pressure can actually make it run better at low and mid-range. Open pipes are really only good for wide-open throttle. I'd gladly give up a bit of top end performance (1% of riding time), for better performance at low and mid-range (90 % of riding time?)
 
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