Misfire

[Sixpack]

Looking for some advice again I'm afraid. I have a 1200gs 55plate and on Monday it started to have a slight misfire at half throttle in 6th gear. I set off home from work and it seems to be doing it in every gear now. It only seems to do it at half throttle, when the throttle is fully opened it's like hitting a power band and off she goes. I don’t know if it's significant but i fitted a full Bos system about a month ago and it's felt like there has been some flat spots but nothing serious. I was going to try swapping the exhaust back over to standard to see if this helped what do you think?
Thanks,
Sixpack

 

[harry]

I'd be more inclined to think you have a fuel system fault or a sensor problem.

 

[Deleted account 211025001]

The Bos will smooth out and to an extent remove any flat spots so I doubt that's the problem.

More likely a coil braking down or dodgy connection in the coil/spark plug area.

Did the problem start (soon) after you fitted the exhaust If so you may have disturbed a connection under the pots when removing and replacing the O2 sensors.

HTH
Andres

 

[millard]

I had a secondary coil break down a coupla months back and the symptoms were slightly different from Sixpack's.
The misfire/backfire would only occur on higher throttle openings whereas his seem to disapear when wide open.
millard

 

[cookie]

duff spark plug, or possibly coil pack IMO.

 

[Brian ROSEN]

Hook it up

The easiest (and perhaps the only) way to locate this is on the computer at the dealers. I had a similar problem, rode straight to the dealer and it was put right in 2 minutes; don't ask me what the problem was - they mumble about 'mapping, updates etc; Never seem to mention tappets, valves, coils, jets anymore!

 

[Sixpack]

The new exhaust has been on for about 1000 miles now and still sounds ace so I'd be very happy if it wasnt that. I'll check the plugs and connectors and as a last resort I'll take it to the dealers. A work mate mentioned it could be bad fuel but would this not affect it at all throttle openings.
Thanks,
Billy

 

[Deleted account 211025001]

The new exhaust has been on for about 1000 miles now and still sounds ace so I'd be very happy if it wasnt that. I'll check the plugs and connectors and as a last resort I'll take it to the dealers. A work mate mentioned it could be bad fuel but would this not affect it at all throttle openings.
Thanks,
Billy

Hopefully you'll find something that's quite obvious but diagnosing a failing coil is not easy and probably a dealer job - agree that it doesn't sound like a fuel quality problem.

Let us know how you get on.

Good luck.

Andres

 

[Sixpack]

Update

On Friday I removed the exhaust and refitted it checking all connections along the way. Some of the bolts didn’t feel very tight but nothing to write home about. Took out the plugs all looked ok removed all connectors I had access to and cleaned and refitted them. Started the bike up and took it for a spin still felt a slight misfire but only a couple of times. Went to the garage filled up with petrol then went for a 20 mile run and no misfire at all. I went out Saturday night for another 20mile run and again no misfire. Into work this morning and running sweet as a nut.
Hopefully it won’t happen again but I'll keep you posted if it does.
Thanks for your help,
Sixpack.