bad air cut off valve?

[oldwings 78]

Hi guys,
I'm starting to notice an infrequent small backfire coming from the left muffler. The bikes warmed up, the tune up is recent and the carb sync was spot on at last check in the fall. I replaced the air cutoff last all also. The bike pulls from idle to top end as well as ever and pops a little on deceleration. The idle seems just a little rough @ 1000 rpms but is smoother @ 1200. The carb rebuild is one year old and was done using instruction from Randakk . I am headed to the shop now to read the plugs and to make sure nothing loosened up on the carb sync.
Any ideas?
RIDE ON,
terry

[pierce]

Is this at idle, or all rpms? At acceleration, or only when the throttle is rolled off when coming to a stop?

[oldwings 78]

the backfire is rolling off throttle from highway speed. thanks for responding.
RIDE ON,
Terry

[Whiskerfish]

Take each of your mix screws out an additional half a turn.

[oldwings 78]

Thanks Whiskerfish,
I'll give it a try.
Terry

[oldwings 78]

Just a quick update. I had bought gas at a little mom & pop store the last time. It didn't occur to me then, but from what I can tell they don't sell much gas. I gave it the sniff test and could smell varnish. I dumped the tank into a pail and not only was the gas old, but there was water in it. Drained the carbs, filled with fresh gas and problem solved.
RIDE ON,
Terry

[rcmatt007]

so my thought is, you might have some old gas with water in it..... see if replacing it works

[Whiskerfish]

Dang Doctors always jumping over the important stuff

SNIP Drained the carbs, filled with fresh gas and problem solved.
RIDE ON,
Terry

[rcmatt007]

I always tell the residents and students.... it is all in the history