Single backfire?

[Techno]

I went to fire up the bike yesterday and after a couple of presses of the go button "boom" it had a massive backfire (which coincidentaly hit the garage door :() then it started and ran perfectly as usual.

What could cause it to do that?

I've been riding it most days, the only thing I can think of is that I had to switch to the reserve tank a couple of days before could it have been a bit of crud?

[MSTRS]

Most likely unburnt fuel down the exhaust pipe from turning over without firing. When it did fire, the gas in the pipe ignited.

[slofox]

Back in the olden days when I drove my Dad's vehicimickles, it was rated as "fun" to switch off the ignition key when driving along, keep the accelerator down for maybe four five seconds and then turn ignition back on. If you did it right you got a big fat backfire when all the unburnt gas that passed into the exhaust system lit up...

But I got in the shit because one day the muffler fell off and he reckoned it was my fault...

[MSTRS]

Ha! Fell off? Nope. But exploded? Yes.
Oval profile became circular, with no end plate...

[slofox]

Ha! Fell off? Nope. But exploded? Yes.
Oval profile became circular, with no end plate...

Well...yeah - something like that...:o

[Techno]

Most likely unburnt fuel down the exhaust pipe from turning over without firing. When it did fire, the gas in the pipe ignited.

Ohh sweet, I was a little concerned as it has never done that before.