Misfire no.4 cylinder

[drydockdavies]

Yes.

Tried a new o ring, didn't make any difference.
I have already swapped plugs, caps, coils which are all new anyway.
Went for a short run today, misfire still there until half mile from home were it chimed in and pulled hard. I will check plug condition and a cold start tomorrow if possible.

[warren3200gt]

4. A coil issue would affect cylinder 4, but also No. 1 so not likely to be a coil I think.

I'd say not 100 % Gray. I've once had a coil where one lead was fine but the other ittermitant. Both leads share all the same coil components Except were they split to feed each HT. I swopped out the coil but assume the spike and ht lead on the original coil were loose or corroded.

[gray]

agreed, but if you swopped the plug leads over 1 to 4 and vice versa the misfiring cylinder would move, so you would know it was a plug lead issue somewhere - possibly as it exited from the coil

[drydockdavies]

Update. I took the Zed to a classic bike show, the bike ran badly all the way there. Chatting to a few about problem but no one came up with anything I haven't tried. Set off for home and about a mile down the road she spluttered and came on all four full power! Several ride outs since and all good, only thing that remains is no.4 is much cooler at tickover and a bit lumpy on takeoff. I've drained the bowls a dozen times and found nothing! I'm baffled but she's running. Full strip over the winter I think.

[gray]

if you're thinking of taking the carbs off in the winter that's ok, you could use some carb cleaner with a thin flexible nozzle to do what i call a " reverse flush"
grit or particles get in the passages , which in the case of the pilot circuit , get narrower and narrower as the passages approach the engine side of the carb. Ends up as a pinhole in the base of the inlet venturi , just after the slide.So flushing from the airbox end won't necessarily dislodge them, you have to put the nozzle of the cleaner up again the pinhole and blow it backwards towards the airbox end. Cutting the carb cleaner's plastic nozzle at a slant, and holding the tip in surgical forceps against the tiny hole works, with 1 hand while pressing the trigger with the other hand , I find.

[drydockdavies]

Yeh we'll give that a go, and a good soak in the ultrasonic cleaner!