Bonneville America Forums Forums Technical Forums General Tech Backfire

What would make my bike backfire when I start it? It doesn't do it everytime, but I still don't like it when it does. It appears to be only on one side. Could the timing be slightly off, to much gas in the cylinder? I've been told that to many backfires can burn the edge of the valve. Any thoughts? Chy?

Thanks, Paw.

I've always thought a backfire was a symptom of a lean fuel mix condition. Might be a half turn out on the mix screw on the backfiring cylinder is all you need to do to adjust it out.

Do you crack the throttle when you start it? If so you shouldn't. Backfires are more of annoyance than anything.. no damage done really but it might scare your chickens or blow off your vacuum caps.... that being said, I'd check those for cracks or being missing. Backfires through the carbs can blow up your airbox though... through the pipes mostly just scare people. (hee hee)
We need to get together for supper soon anyway so I'll give it a once over then if you'd like.

Throttle when starting will definitely do it. Just use a little choke. Seems like even with the engine warm a bit of choke makes it start quicker.