Just developed a misfire at 3000rpm ish. Any Advice welcome

[TangibleSolid]

Thanks for looking.
Bike is a 1150 GSa 02 reg, single spark, 25K miles

She developed a misfire at about 3k rpm so I changed the plugs and all seemed to be fine for a couple of weeks. Now the problem has returned mid-ride (bike ran fine for first 50 odd miles then just started misfiring as described below), so I've changed the plugs again for a set of known good ones but the misfire continues.....

If I drive the bike gently it pulls without problem all the way to the red line but if I 'squirt' it at about 3-4K (just where I need it for safe overtakes) it misfires terribly, 'bogs down' then clears and goes ok.

I've checked fuelling and all seems ok, got fuel, fuel pump works ok, fuel pressure seems ok (although I don't know how to check exactly), new fuel filter fitted about 2K miles since, throttles balanced, TPS checked and ok, throttle cables all seated correctly etc, etc.

So I'm thinking, coils breaking down under load, but I would appreciate any other advice (maybe hall sensor ??) I don't want to 'invest' in a new coil if un-neccessary.

What do you think?

Cheers

 

[Packer]

Mines a twin spark but suffered similar problems when the stick coils failed.

Actually I'm not certain that you have stick coils but pull off the cover from the rocker boxes and extract whatever attaches to the deeply buried spark plug. If it is a rusty metal tube that may be your problem.

 

[davegs]

Flog it quick!

 

[TangibleSolid]

Definitely not stick coils as bike is single spark and doesn't have 'em but thanks for the input.
Re second suggestion, I think I'll keep it a while longer. Cheers

 

[GSART]

Check the plug leads for splits.... it could be arcing.

 

[davegs]

Check the plug leads for splits.... it could be arcing.

Look at it in the dark, easier to see arcing.

 

[DrFarkoff]

Don;t put yer finger on them! If they are arcing

 

[TangibleSolid]

an update (and a question)

right.... removed the coil and HT leads. there doesn't appear to be any damage, cracks etc on either the coil or leads, in fact they appear to be in very good condition.
I put a test meter across the coil (LT and HT) contacts as per the Haynes manual and got the following results
Low tension 0.9 ohms. (Manual says it should be 0.5 ohms)
High tension 7.5k ohms (which is as per manual)

So the question... does the low tension measurement suggest that the coil is faulty??

Thanks