Afterfire

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What are the causes of afterfire?
As far as I can tell, An overly rich fuel mixture fails to be ignited in the cylinder and instead, ignites inside the hot exhaust, Am I right?
I've only just realised that what I have been calling "Backfire" is actually "Afterfire"
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Riding: Yamaha RXS100
Aiming for : RD350 + Test
Dream bike: Suzi RG500 Gamma

[G]

Pretty much everyone calls them 'backfires', though technically that's through the carbs I believe.
They can be easily intentionally caused by dumping too much fuel into a hot exhaust (ideally a steel race exhaust) - flick the kill switch off while going down a steep hill with the throttle open on a carbed bike with the above configuration and you'll be scaring grannies for miles!

However, can also be caused (usually at lower revs on throttle/idle) by an air leak in the carb area or the exhaust.

[smegballs]

Usually caused by air leaking into the exhaust. Seeing as there is always unburnt fuel in the exhaust gasses, oxygen (concentration and distribution) is normally the limiting factor in combustion. If there is an air leak then hot exhaust gases can mix with fresh air and cause combustion.

This is just one cause of afterfire/backfire and there can be a fair few other reasons. I find that having a two stroke backfire is very rare and it sort of sounds like a muffled sneeze than a proper 4 stroke bang.

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