Backfire

[Val]

My Fazer lately has started to backfire when cold in the morning. Not always but sometimes

Do I need to do some servicing?

It has new Iridium spark plugs.

I have the feeling all started after I have changed my old air filter with new K&N.

Any ideas?

[Brettholmes89]

Is it back firing just on tickover? Mine back fires if I've been giving it some beans then roll the throttle off

[Val]

Is it back firing just on tickover? Mine back fires if I've been giving it some beans then roll the throttle off

Only when starting in cold.

[Brettholmes89]

I know it's a car thread but the principles are the same.
Worth trying them.

http://www.viva-lancia.com/fulvia/qanda/engine/backfiring.php

[His Dudeness]

Only happens on warm up? Does it only happen with the choke on?

[Jamieg285]

If you've just changed the plugs it could have significantly changed the spark/fire characteristics, meaning you don't need as much choke angle/duration as you are used to.

I've recently changed my for the first time since owning the bike.  Before the change I needed choke on for a couple of miles before I could take it off and not stall.  With new plugs I can take it off after a couple of hundred yards.

[Frosties]

May just be a bit of condensation in the exhaust Val - just a thought.

[darrsi]

Mine did it the other day inside my shed, and made me bloody jump, but i now realise it was probably connected to my side stand switch issues, so was just over fuelling because it didn't wanna start with the side stand down for whatever reason.

[Val]

Only happens on warm up? Does it only happen with the choke on?

Yes only on warm up when on choke only. I do twist a nudge of throttle when starting on choke. I know it is recomended not to use any throttle when on choke, but if I not use at least a little throttle the bike can't start.

If you've just changed the plugs it could have significantly changed the spark/fire characteristics, meaning you don't need as much choke angle/duration as you are used to.

I've recently changed my for the first time since owning the bike.  Before the change I needed choke on for a couple of miles before I could take it off and not stall.  With new plugs I can take it off after a couple of hundred yards.

Actually I have changed the plugs some time ago last year and it was working fine. The whole backfire started after the K&N filter.

I will buy soon OEM filter and will see what happens next 

[darrsi]

Surely a carb balance would actually help to even things out?