Backfiring from Exhausts

[Jayy]

Seen them a few times and they sound like gun shots being fired... what's the deal with them? Something to do with the engine or the exhuast?

[Paulington]

[Stelmer]

One of the little perks of having a carbed bike.....

It's unburnt fuel igniting in the exhaust. Most excellent when done in tunnels, the best being that long one in Birmingham

The way to do them I find is, drop down a gear or 2 when going downhill so the engine revs high (and should warm up the downpipes more), flick the killswitch off with the throttle open, close it and turn the killswitch back on. The exhaust has to be hot though.

Others will probably have better methods...

The result should be a rather loud bang. Effective at night, in tunnels, or crowded city centres.....

[angryjonny]

My fuel-injected VFR used to backfire like a beast until I had new downpipes put on it... a bit of unburned fuel and heat from the exhaust came together - the hole in the pipe provided the oxygen and bam.

It freaks people out at 8:30 am in leafy Chiswick.

[rhone81]

Backfired it a while ago going under a bridge only for the engine to cut out. "Bollocks!" as I thought I'd knackered the engine, pushed the bike onto the pavement and then realised I had flicked the kill switch on again

Before the people with beards (BMW owners) come along to say we should be concentrating on learning good road position, here's a pic of me backfiring last winter:

[Im-a-Ridah]

Nice road positioning...

the pictures pretty good too

[Chriss]

My SV does it because of the pair system on it.
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TheShaggyDA: I've got 3 or 4 pairs that predate my wife, so at least 11.5 years old.