Muffler backfire on Throttle let off

[kent56]

I have 2011 Ezgo Custom. Had carb recently rebuilt because of bad needle valve. muffler backfires ever so often when leting of throttle or slow acceration. Is this an air/fuel mixture problem. What is the number of turns on the air mixture screw. I have taken as much slack out of the throttle cable as possible. Thanks

[Heliarc]

If you had a shop do the carb rebuild and it just started backfiring when you got it back, the shop messed up.

Just to be sure though, is it when you let off the throttle, or when you get back on?

[kent56]

I am thinking when I let off throttle.

[Heliarc]

Ok, I know usually what to do if it backfires when you get on the throttle but when you let off I'm not sure. I don't believe it to be in the carb if it runs fine besides the backfiring though. Usually backfiring, technically "muffler explosion" even though it doesn't explode, is caused by something in your ignition system screwing up. If it's working well besides the backfiring I wouldn't mess with any mixture screws or you're likely to compound your problem. Unfortunately I can't really tell you much more. It could be a weak coil, an intermittent connection, fouled plug, bad wire, or may indeed be the carb settings.

My first move would be to call the shop that serviced it. If the backfiring wasn't present when they took it in they ought to make it right. If it was backfiring when you brought it there I can't imagine why they'd give it back to you in such a condition.