an impending knock of doom?

[tripe]

Recently noticed when waiting at the lights that every now and then the engine seems to "bump" as if its missed a beat or been hit with a hammer, I can't think how else to describe it
Its rather disconcerting.
It seems smooth and untroubled whilst on the move. It was serviced 1k miles ago. It had done it before the service and still does. Jap and German looked at me blankly when I mentioned it and found nothing.
Any thoughts
Henry

[bigblackfalco]

Sounds like a misfire/ missing sparks. Maybe check the HT leads?
Bailey.

[horse27]

Tell you the truth mine does the same ...

Was worse once when I serviced it and over oiled the K&N ... I think that was the cause anyway.

After another service recently it is all back to normal again. But the "stutter" does come back from time to time at tickover.

So - what am I suggesting ... it's not a knock of doom, rather more a fuelling thing? Throttle balance perhaps. Also, make sure the throttle cables are seated properly - that was a simple fix for me in the past (forget who told me). Free play in the throttle cable too.

Cheers.

[Bender]

Sounds very much like the spark plug coil packs.

They can be change in 2 minutes, but can be pricey if you get new ones, try Motor Works for used ones...

[tripe]

thanks for the advice. Will see if it deteriorates and then panic when it does

H

[tripe]

oh bugger
start up this morning took a good ten "revolutions" rather than the usual two or three before coming to life. Thought it wasn't going to start. It then felt very muddy as if only firing on one cylinder. After going about fifty yards it all became as smooth as usual.

Will see what happens later when i finish work but any further thoughts
HT leads, coil packs?
H

[Parky]

I have just bought my old bike back which I sold last year and it's doing the same thing.It seemed to take a while to start and vibrated at certain revs. Swapped the paralever bearings put on some new hoops(cured the vibes),done the valve clearances and plugs but it still skipped a beat at tickover so I took it to dynobike in the local town and he checked the throttle bodies (out by a mile)discovered a corroded wire on left injector connection that when waggled caused it to miss.He cleaned the terminals and put them through an ultrasonic cleaner to improve the spray pattern too.Sorted I thought but no it still does it so can only be the coils or leads?
Pretty scary sound when it does it sometimes you think that your going to be making eye contact with engine parts soon.
Parky..

[tripe]

as I was wearing earplugs i wasn't really aware at how loud the poor thing sounded. When I got in to work there was a message from my wife who had jumped out of bed thinking that the bike was about to explode under me and had rushed to the window expecting to see me vapourise!

[moon]

Recently noticed when waiting at the lights that every now and then the engine seems to "bump" as if its missed a beat or been hit with a hammer, I can't think how else to describe it
Its rather disconcerting.
It seems smooth and untroubled whilst on the move. It was serviced 1k miles ago. It had done it before the service and still does. Jap and German looked at me blankly when I mentioned it and found nothing.
Any thoughts
Henry

mine did the same thing. Just changed the 2nd coil. fixed!