Possible misfire this morning?

[cortinaman]

Hi everyone.

When starting her up this morning there was a loud bang like a shotgun being fired simultaniously with me hitting the starter ( withing a fraction of a second after pushing the button). I thought it might have been something behind me, but i noticed people looking in my direction and I can't really think of anything else happening in my street at the time either. Obviously i got a bit startled and let go of the button immediately. Anyway, thougt it might have been a misfire and pushed the button again and she started like normal. Everything was fine and the ride to work went smoothly as always.

Now, this really puzzles me as there has been nothing out of the ordinary exept this incident. Parked as normal friday afternoon, weather conditions fine both on friday and today, a few showers of heavy rain during the weekend though. I would understand this if I'd had to crank her for some time allowing fuel to enter the exhaust, but the bang came immediately.

Curvy half faired, got the bike in April at 10000 km on the clock, currently 16000 km, good service history, no problems earlier.

Any thoughts?

Regards,
Frode

That's happened to me a couple of times in the three years I have had mine.

I wouldn't worry about it, but it does startle you I must admit. When I mentioned it to a fellow biker he said it was probably unburnt fuel lurking around the exhaust?! No idea myself!

Tony

[Sid Squid]

Originally Posted by I previously

If you fire up your bike from cold in marginal conditions, it's not unusual to get either a partial, or sometimes a complete misfire, the resulting unburnt fuel rich gas gets shoved into the pipe on the exhaust stroke, next charge goes into the cylinder, fires, and then extremely hot gas gets let into the pipe where aforesaid eminently burnable gas lies waiting to p*ss your neighbours off, voila!, Big bang in the pipe.

Enjoy.

Possible causes:

Plugs need a clean/change.
Battery voltage low: Poor quality and duration sparks.
Old or contaminated fuel.
Incorrect choke setting.
It's bloody cold out.

The wife thought I had shot myself in the garage when this first happened to me.

[cortinaman]

Tnx guys. Yeah, that's what I thought.

I've had misfires like this before, but never on the SV. My old Norton with kick-start is notorious for this, she can kick like a mule and really needs a firm hand (or foot) sometimes.

But there's always been an explenation, bad weather, prolonged cranking leading to fumes in the downpipe, less then firm foot etc.

This time there was nothing to explain it. Stopped as normal when parking, excellent warm and dry weather, .... backfire on first rotation of the engine. I don't see how anything could have collected in the downpipe. Or maybe my mind is playing tricks on itself and the engine actually cranked for a few rotations before deciding to have fun with me?

She's shown no sign of misbehaving after so I've put my mind at ease. Guess there's a first time for everything, eh?


Frode

Originally Posted by Sid Squid

Sure about the last one?

Just had a massive misfire there and the bike wont start now, bloody weather!


And my head is sore from the noise of it!

hmm mines done something like this today except first trying to start it and there was nothing i mean nothing absolute silence tried 1 second later and it fired but realised the choke wasnt on lol then the big bang came but im used to it as mine is always popping and banging love it

I got a bang from under the petrol tank today, after that the engine cut out instantly. Restarted it and got several small pops but kept running. This was only 5-10 seconds after starting it up. Cold weather? Loose spark plugs?

Definitely the cold weather, im gonna put the battery on charge and attempt to get the plugs out, last time i could loosen them but not get them out as the socket wouldnt hold it to pull it out any suggestions how to entice it out of its hole...

Cheers