Puff noise

Morning all

Can anyone explain what might cause my bike to make this kind of puff noise from the front cylinder every now and again, only done it like 3 times in a week and always when i blip the throttle when stationary, normally not long after startin maybe 5-10 mins, i put it down to a cold engine but just wanna be sure.

Originally Posted by daveyrach

Morning all

Can anyone explain what might cause my bike to make this kind of puff noise from the front cylinder every now and again, only done it like 3 times in a week and always when i blip the throttle when stationary, normally not long after startin maybe 5-10 mins, i put it down to a cold engine but just wanna be sure.

Sounds exactly identical to my misfire, that little puff is a huge bang with the air box off Ive not gone all out to find it, mine was rear cylinder, i was unfortunate enough to have it happen whilst looking into the rear carb. I **** myself.

Originally Posted by beabert

Sounds exactly identical to my misfire, that little puff is a huge bang with the air box off Ive not gone all out to find it, mine was rear cylinder, i was unfortunate enough to have it happen whilst looking into the rear carb. I **** myself.

I nearly ****ed myself laughing at my desk then, i have a really funny image in my head!

Like i say 3 times in a week, shouldn't cause any probs should it??

[mikerj]

Back firing through the carb is often caused by a weak mixture. Since you have a curvy, and it only happens when the engine is cold, it suggests maybe you are shutting off the choke a bit early.

Thats probly the case i do shut it off quick as i don't like to wake the neighbours lol. Will have to leave it on longer see if this cures it.

Originally Posted by daveyrach

I nearly ****ed myself laughing at my desk then, i have a really funny image in my head!

Like i say 3 times in a week, shouldn't cause any probs should it??

i tripped backwards from shock lol.

I haven't got round to figuring out why, as its so infrequent, and my plugs were a perfect colour when replaced not long ago. If the frequency increases ill start looking.

Heres a video of one on ebay doing it.

Mine wasn't like that though, mine was bright yellow flash, no smoke and louder. Just realized my mate from another forum has posted a response, like mikerj said above ^ weak mixture vacuum leak.

Lol, yeah mine is the same very in frequent and i checked the plugs on Sunday and they were the perfect tan colour

Hasn't done it again since but today on my way to work i was belting up the road engine around 8-9k and the light ahead changed so closed the throttle got a 'puff...puff...puff...puff...puff' exactly the same as the other times but this time i was doing about 40-50mph and slowing down and the engine was warm running about 30mins thru town etc.

Tries to make it do it again but nothing, could it be where the chap before me had it, it just sat in his garage barely used and now i use it everyday its clearing itself out?

Like i say i changed oil, filter and checked plugs last weekend.

Rip them out clean them thoroughly and at the same time if there is an air leak, you will fix it as you put them back.

apparently the pair system can make this happen, well it does on a race car (road engine)