chirping from left muffler

seattle##gs

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Oct 28, 2014
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I read on this forum that commando mufflers used to chirp long ago...news to me. One chirps and the other doesn't. I thought something must be wrong?
 
Depends on the internals like the BSA Goldie twitter, so you have mixed mufflers.
 
Two new EMGO mufflers, left side chirp. Swapped sides, still left side chirp'ed. After I while, gave up trying to find it and decided it was a Norton "thing". Loosening, slightly moving things, and retightening got it down to random chirps.
 
On my 72 750, the left side plug was always a little lighter in color than the right. EI so sparks and timing should have been the same. Carbs set up exactly the same, both air screws 1.5 turns out. Either running a bit hotter or a bit leaner. By chirp do you mean a light pop when you close the throttle?
 
My 850 chirped on left with the muted peashooters bike came to me with. Was planning to bore out the welded in mutes, even got a larger step type drill bit for the job. Before I could muster up enough courage for the job, I came across as nice pair on unmuted peashooters locally for a low price. Soon as I removed the originals, found left one had a rattle from within, so that likely the cause. Replacements had no rattling and no chirping.
 
When I have a colourtune fitted to my 750 it chirps like a Goldie Coming down the mountain
 
baz said:
When I have a colourtune fitted to my 750 it chirps like a Goldie Coming down the mountain
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Yes I too found the colourtune plug changed the exhaust note significantly out the side it is on. Don't quite understand why. Perhaps the spark from the special plug is somehow changing the combustion event in that clyinder? Bit like the observation of the combustion event changes it, just like Quantum Mechanics theory stipulates ;-)
 
It is a chirp not a twitter. Like a bird. Hearing it I assume the worst, and convincing the customer will sound like making excuses. I've listened up and down the entire exhaust pipe and the sound seems to be in the muffler area but that's still a maybe. I will try swapping the mufflers.
 
seattle##gs said:
It is a chirp not a twitter. Like a bird. Hearing it I assume the worst, and convincing the customer will sound like making excuses. I've listened up and down the entire exhaust pipe and the sound seems to be in the muffler area but that's still a maybe. I will try swapping the mufflers.
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Yes, very frustrating especially when a customer is involved. Try this - I plan to next time I have one. Loosen the muffler to exhaust pipe and see if it changes. I got the last one down to a random chirp by loosening and tightening muffler mounts, but I don't remember loosened the muffler clamp. If that doesn't help, try loosening and tightening the exhaust rose while hot and running. I really don't think the muffler itself is causing it since when I swapped mufflers side to side, it stayed on the left.
 
And the prize goes to Mr. Marsh.
I removed the exhaust pipe and examined/felt the union of flanged spigot to exhaust pipe. It was not smoothly blended in like most pipes. I replaced it with another used pipe and the chirp disappeared. The idle improved, too. So next time you have your pipes off give them the once-over. Even a small difference here makes a noticeable difference...and not for the better
 
seattle##gs said:
And the prize goes to Mr. Marsh.
I removed the exhaust pipe and examined/felt the union of flanged spigot to exhaust pipe. It was not smoothly blended in like most pipes. I replaced it with another used pipe and the chirp disappeared. The idle improved, too. So next time you have your pipes off give them the once-over. Even a small difference here makes a noticeable difference...and not for the better
Click to expand...
chirping from left muffler
 
seattle##gs said:
And the prize goes to Mr. Marsh.
I removed the exhaust pipe and examined/felt the union of flanged spigot to exhaust pipe. It was not smoothly blended in like most pipes. I replaced it with another used pipe and the chirp disappeared. The idle improved, too. So next time you have your pipes off give them the once-over. Even a small difference here makes a noticeable difference...and not for the better
Click to expand...
I had to grind flush the inside of the flanged spigot on a Commando Specialties seamless silencer as the weld at the shoulder had a knob on it that prevented the header from inserting fully.

That same pipe fractured after 1000 miles.

chirping from left muffler
 
gortnipper said:
I had to grind flush the inside of the flanged spigot on a Commando Specialties seamless silencer as the weld at the shoulder had a knob on it that prevented the header from inserting fully.

That same pipe fractured after 1000 miles.

chirping from left muffler
Click to expand...
I never use silencer clamps
 
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