Initial Live Kick Backfire

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tcb-1
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Initial Live Kick Backfire

#1

Post by tcb-1 »

Got a puzzlement here, gang.

My usual starting process goes swimmingly until the first "ignition on" kick. Then it ALWAYS backfires through the exhaust.

So I:
1. Turn fuel on and set the choke.
2. Fully retard the timing.
3. Kick twice with half a twist on the throttle. (The carb is now primed nicely.)
4. Turn the ignition on and kick though.

If I give it an swift initial kick through, the backfire is fairly loud. If I give her a wimpy initial kick through, the backfire is noticeably less loud. Then that's it. A couple more live kicks (without backfires) and it fires right up.

Is this a timing issue? Am I retarding it TOO much during the initial kick through?

It's not that big of a deal since she's running good now, but it sure is embarrassing at bike night :oops:
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Re: Initial Live Kick Backfire

#2

Post by FlatHeadSix »

TCB
I would recommend more gas and less retard. The Rider's Handbook says to kick the bike at full advance, or nearly so. The "nearly so" is not very quantitative but you get the idea, try retarding it only slightly. Backfires are usually a result of lean mixture, try an extra primer kick or a more open throttle when you give it the ignition-on kick. Every bike has its own sweet spot, expirement a little and let us know.

This all assumes, of course, that your timing is set correctly and you have no intake manifold leaks.

good luck!

mike
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Re: Initial Live Kick Backfire

#3

Post by jdpan »

As long as you're sure it's getting enough prime, it sounds like a timing issue. Try a little more advance and see what happens, if it gets better, investigating your timing may be in order. .. Thats what I'd do.
tcb-1
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Re: Initial Live Kick Backfire

#4

Post by tcb-1 »

Stands to reason guys. I wasn't barking at me until after I adjusted the timer about 2 degrees clockwise (retarded). Let me give it a try with it advanced a bit more. Might be an easy remedy......
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Re: Initial Live Kick Backfire

#5

Post by tomfiii »

That backfire is from the wasted spark igniting gas with exhaust valve open. Try 1 kick full choke or 2 if cold out and 1 kick choke 1 notch on with throttle closed,then kick with just a little throttle,if no fire after 2 kicks or so try wide open. {linkert!} As always everybody is different.
tcb-1
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Re: Initial Live Kick Backfire

#6

Post by tcb-1 »

Yep that was it. I was retarding it too far. I tried a bit more advance and no backfire. Thanks guys for the suggestions!
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