Bang when starting the bike

[flamegrape]

Tonight when I started my bike, there was a loud BANG from the back end - assuming it was from the exhaust - this is the second time in a 4 months it's happened. I can only describe it as a firecracker going off behind you when you hit the starter button!!

It's going into Kawasaki on Monday for a look over cos it's sounding a little ropey with a feint tapping sound under the tank when on the throttle.

Anybody any ideas - please??

I'm beginning to think girls are less trouble!!

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Jonny (Riding his Kawasaki ZX6R J1)
It's one big learning curve right now

[Moo.]

Back firing

Unburnt fuel in the exhaust, when it heats up, explodes. Usually sounds like a gun shot xD
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A2 Passed 18/6/10

[flamegrape]

[radical]

It can happen when the bike is turned of by the kill switch instead of the ignition resulting in unburnt fuel lying in the exhaust.

[flamegrape]

It's carbs.
I never use the Kill Switch.
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Jonny (Riding his Kawasaki ZX6R J1)
It's one big learning curve right now

[Wafer_Thin_Ham]

My Hornet used to do it once in a blue moon. I never worried about it....
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[evoboy]

My J1 also does it when its been sat for a while. Never been worried bout it and it doesnt seem to do any harm. 54k on that motor!

They do tap and rattle a bit, even when in good working order.
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Suzuki GT250 x7------- Fazer 600------CB250RS------Aprilia Rally 70----- Bandit 600

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[Kickstart]

Hi

How much of a bang? Small pop won't take much fuel, but more than that probably means a decent amount down the exhaust. Possibly from a leaking needle valve in a carb.

My FZR did it once loudly enough to leave my ears ringing for a couple of hours . Suspect on that it happens as the float bowls are linked, and parking on the side stand allows fuel to drain down to the l/h carb to a high enough level to flow out of the jets into the engine.

[flamegrape]

[stevo as b4]

The 6R's just do it TBH! Mine did it now and then too. It can happen when starting from hot, as the 6R J-series is a por hot starter, and i think it's because heat soak causes fuel evaporation from the carbs. If you keep trying to start the bike with the throttle open, or use the choke then you can easily overfuel the motor slightly and then it can happen.

The ZX is a bit rattley and rough at tickover and under mild load than say an R6 or CBR6, and they all sound a bit rattley and loose. just make sure that your valve clearances are checked in accordance with the service schedule, and then don't worry about it. The rough and gruff sound of a kwak IL4 is what gives them the character that Honda's and other bikes seem to lack.

[flamegrape]

Cheers stevo as b4.
Good post, thank you!

Sounds just as mine is. Can I just ask - how would I check the valve clearances? Is this best left to a mechanic?
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Jonny (Riding his Kawasaki ZX6R J1)
It's one big learning curve right now