Backfire on start up, what causes it ?

[greenstiles]

As above, had bike for about a month, not happend before, but came back from a long ride, nipped in the house, came back out, started the bike and it backfired on start up ? valves starting to play up ?

[rigwit]

Lot,s of thing can cause it.................b4 delving does it happen every time bike is,(hot) started, cold started ?

[a_morti]

I had this once when I first got the bike. Never worked out why but a new battery sorted it.

[greenstiles]

Just happend once so far, engine hot......new battery with good charge, starter sounded weak to me ! ? it was a carb/ air back fire not exhaust.....will see if it does it again

[rigwit]

you have mentioned that your one exhaust pipe was u/s,         if air was pulled into the pipe then it would backfire..

[greenstiles]

u/s ?

[Daveontheedge]

U/S = unserviceable

[a_morti]

U/S = unserviceable

Is that Canadian for NFG?

[greenstiles]

Ahh, no gonna get a chap to weld new header collers on, don't think it's leaking there but could be....

[Drewski]

Backfire on start up. What causes it?

Unburnt fuel in the pipe igniting. Do you start the bike with Wide open throttle, (WOT)?

[greenstiles]

usually have to open the throttle a bit to get it started