Backfire on startup (choke?)

[ogriofa]

Hi All,
I have a 2003 650.

When starting it up in the mornings (with choke) I sometimes get a backfire.
Is this normal? Does the 650 exhoust have a tendency to "cake up"?

Thanks,

[Austin]

Hi All,
I have a 2003 650.

When starting it up in the mornings (with choke) I sometimes get a backfire.
Is this normal? Does the 650 exhoust have a tendency to "cake up"?

Thanks,

I use my choke only when the bike has been unused for more than a couple of days AND it is below freezing. If I try and use it any other time I often get a backfire too. I assumed it is excess petrol getting into the exhaust and then igniting. TBH I don't give it a thought, its just one of those things.

[z-weiser]

my vara sometimes does it too - i just ignore it but it generally scares the cr*p out of any nearby wildlife!

Z

[largewayround]

Yip my TA did this last oct when my wife was standing behind , she nearly dropped a haddock..

[thekeyman]

l too rarely use the choke but when l do on my 650, it never pops. l am convinced that the Alps are set up rich but l,m too lazy to put smaller jets in. l start with no throttle on at all and once started pull in the clutch for about ten seconds to free the plates and get rid of the rattle.

[tizzi]

I turn mine over for a second with the cut off switch 'off', then start it normally. I find the colder it is, the more likely it is to backfire. Maybe it's more to do with a sticky valve due to the oil being thick rather than fuel in the pipe.

[btbloke]

There set up to run really rich anyway,it gets ridiculously rich with the choke on. A residual amount builds up after a couple of seconds,unable to be burnt in the "hot box" part of the exhaust and hence backfire.I should only do it once or twice or you might notice a mild popping coming from the exhaust this is the same thing.
I start mine on the throttle then adjust the tickover with the knob next to the carb,idle it at about 1500-2 grand for a couple of minutes then adjust it back down to a sensible tickover to ride.I've always been a bit concerned over washing all the oil from the bores with too much juice from the choke.
only a suggestion,might be worth a try.