Bonneville America Forums Forums Technical Forums Exhaust Pop on start

Ok. Everytime I start the bike up over the last 4 days or so, the first thing you hear is it starts with one heck of a POP!!!! Any ideas?

Are you cranking the throttle?
Normally you don't have to touch the gas, just pull the choke knob out and hit the starter button.

Yeah, definitely don't touch the throttle when you start it.
You can have a backfire which causes the dreaded
Airbox Ka-Blooey!

Is it a BANG or a PoP? If its a BANG, & it happens when the bike is warm, then that's a sign the pilots (air screws) are waaayy rich.

Still need help...I DO NOT twist the throttle at all. This POP happens only on the first start of the day when she's cold. I pull the choke out and start her, that's all. Then, POP!!!! Then she runs fine but I just can't figure this one out.

Sounds like a mixture screw adjustment is in order.If you do it now in the cold weather thought you will want to do it again once it warms up again since you really want it adjusted for optimal running during peak season.

do you leave the gas valve on or do you shut it off when she is parked??? i know that some of these will leak a little when left on and the float bowls will be top off full and they will pop on start. try this routine, when parking her for the night, shut the gas off and blip the throttle once or twice, then shut her off with the key. in the morning, pull your choke, hit the starter and after starting then open the gas line. just try it and see if that does the trick if not then maybe you need a minor adjustment.

Also do you rev the engine, just before you turn her off for the evening..

Thanks Myke and Ray. Both of these sound like some good advice. I will try both and see if there's any change. If not, I guess I'll look into Ian's post about adjusting my mixture. By the way Myke, I do leave the gas on when she's parked but she on the road most everyday.

I bet you didn't ride today, did you Chris? You need to get some winter gear, bro!

oh look at you Pooh-Bah. Yes, I do need to get some winter gear....and quick. Today was the first day I havent riden.

Ahh, November in the South, had to close the vents on my jacket today.....

You were right Myke. No problems since I started turning the fuel off.Huh. Thanks man.

you are welcome sir!!! i am glad it was so simple.

Please let me know how the pop problem is resolved. I have an '05 America that pops @ first start, especially when the weather is cool, but has done it in warm weather too. Maybe reply to my office email addy?

gmcosker@hunter.com

Gerry
Florissant, MO

Sorry I haven't responded. I thought this thread was dead by now.
Gerry, I shut the gas off and gas the throttle once or twice and let her run for about 15 seconds. Then I shut her off with the key. In the morning, I pull the choke, hit the starter and after starting I open the gas line back up. I know I shouldn't have to do it this way but it does stop the HUGE POP on start and that makes me a lot happier.

Typically mine only bangs/pops on start up when I richen my idle screws too much. If you have played with the idle mixture screws recently and richened them, it could be the cause of the problem. Try turning them in a 1/4 turn.