Bike Running On One Cylinder Shortly After Starting?
 

Hey peeps,

I've got a question that I 'think' I know the answer to, but wanted to get some further opinions on:

Occasionally when I start the bike up, it makes a noise for a few seconds that sounds like it's running with no exhaust. Very loud and lumpy noise. But then afterwards it's fine.

I'm 'assuming' that it's just the engine mis-firing, as the spark-plugs are well over-due to be changed. But wanted to see if you all think the same? Or if it could be something a bit more sinister?

Re: Bike Running On One Cyclinder Shortly After Starting?
 

Does it only happen when the bike's cold, or when it's hot too?

If only cold, then you're right and it could be a plug getting up to temp

Re: Bike Running On One Cyclinder Shortly After Starting?
 

It's only happened recently when the engine is already warm, either due to the warm temperature outside (with the engine temp showing 30 degrees) or not long after the bike has been running (with the engine temp showing around 70/80).

Re: Bike Running On One Cyclinder Shortly After Starting?
 

Any thoughts anyone?

Re: Bike Running On One Cyclinder Shortly After Starting?
 

Evaporating petrol?
Different circumstances, but, recently a right propper head scratcher was solved on one of my bikes. It would only ever ever ever start on one cylinder, sounded like it was thuping itself to death. What was thought to be oil leaking from somewhere(but no evidence) was actually petrol leaking out of the float bowl. There must have been some grit under the rubber gasket inside, so it didn't seal properly. Overnight the petrol would evaporate or leak out of the seal, so there was no petrol in it to fire up both cylinders. YC swapped the bowl and gasket...bish bash bosh TWO cylinders :-)

Might be worth poking about in the petrol dept. Different to carbs, so dunno how it works, but maybe theres a seal gone somewhere.

Re: Bike Running On One Cyclinder Shortly After Starting?
 

Maybe vapor lock in injector pipes. Try change the plugs, see if it helps and see what tey look like.

Re: Bike Running On One Cyclinder Shortly After Starting?
 

It did it again this morning...
I'll change the plugs since I've got some lying around, and see what happens!
(May be some time before I get around to doing that though :p)

Re: Bike Running On One Cyclinder Shortly After Starting?
 

I recon dampness in front spark plug 'ole.

WD40 / dry / silicon grease seal