popping on deceleration

CalAl · Posted: September 9, 2009, 5:51 pm Post subject: popping on deceleration

Now that we're back on the road,I'm working through the details. Lots of pops on deceleration - sounds bad, but I know it's not good. This '77 is stock except for a Mac 2 into 1 pipe. I rebuilt the carbs and went up one size on the pilot jets and up two on the mains, put on XS performance pod filters and raised the needles one groove. The bike starts, idles, and runs good. Compression 145 both sides. Valve adjustment correct.
Thanks

penn71911 · Posted: September 9, 2009, 6:05 pm Post subject: Re: popping on deceleration

I'm thinking one size on the pilot is not enough, you now have free flowing filters and exhaust, it's probably running lean in the pilot circuit still.
Either that, or, less likely, you've got an exhaust leak that's sucking air on decel...

cpt137 · Full Member Joined: Jan 10, 2009 Posts: 97

poping on decel is air getting into the exhaust, pretty common on the mac 2/1 because the pipes just slide in the muffler. Some high temp sealer around the joints should help.

TeeCat · Posted: September 15, 2009, 8:11 am Post subject: Re: popping on deceleration

Guys, are we talking about pronounced popping, or sort of burbling or grumbling? I experienced the same thing on the right side, and tightened my muff clamps where they join the header exits, and it (among other things) seemed to reduce it to a grumble. You might try that first.

Maybe try tightening the headers at the head too, though I don't know the torque rating on that as I have not yet done that.

TC

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