Bonneville America Forums Forums Technical Forums Exhaust Cold starts exhaust backfire.

Good morning all. On my 2006 I have TOR longs, and everything else yet is still stock, but I have turned out the idle mixture screws 3 turns. Lately, most mornings I get a loud exhaust backfire, and it won't start. When I push the starter again it starts normal. This is with the choke out full, and no crankin on the throttle.

This is at 5:30 to 6:00 in the morning - I'm sure that makes me popular with the neighbours!

For the rest of the day it's OK. Could someone explain what's happening to cause this? Thanks.

Do you turn off the gas petcock when you park for the night? If not, that could be why you are getting the backfire when you start in the morning.

That's a good comment, never thought that leaving the petcock open would cause that. Usually I close it, but I do sometimes forget. I'll have to be more diligent.

So if the float bowl fills too much then the initial draw at the start is too rich putting raw fuel into the exhaust? And also, is this an indication of a float valve problem?

I just got my TOR on, I had the same problem this AM (6:00)...I don't turn off the petcock either....mmmmmm will close it tonight and see what happens tomorrow

I really can't answer your questions - way too technical for me...

I have had the backfire on starting before, but it only happens when I leave the petcock open. Someone much more carb-smart (Hey Dinqua!!!) could answer more intelligently on the subject.

Update on the morning exhaust backfire problem. The bike is still backfiring in the morning, even with the petcock closed.

I've noticed that the Pingle gasket has started leaking. I followed the instructions carefully, and after 3000km I thought that I wasn't going to have a problem. The gasket material included with the Pingle seems to be getting soft. I'll have to chase down the pingle leak threads and deal with this.

This is the only symptom that is coinciding with this new backfire problem. But I sure don't know how the tank gasket leak causes the petcock to leak fuel through to the carb to cause backfiring.

For what it's worth and y'all know the answer to that one. But I quit opening the choke at all when starting cold last year. It ticks over and idles smoothly from the "getgo".

Prior to that, with choke open it'd fire right up, but wouldn't settle down to a smooth idle for a few minutes. Granted there's many variations off the same basic setup, or "your results may vary".

jh

A speck of trash could be keeping keeping the floats from really shutting off the flow of fuel to the intake. Does it backfire with no choke applied?

Thanks for the advise - I haven't tried to start it with no choke, I'll try that. Maybe I get to "bang" my neighbours early AM for a while, makes a heck of a racket ! At least my wife still has a grin on her.

I always start her up no choke all year round with the petcock closed. When it starts I pull it out if needed to bring the revs up a bit and open the petcock. You can be too sure with these bikes and their sensitive air boxes.

Willy