Still trying to track down the damn misfire. It's getting worse, and appears to get worse with temperature, so I'm beginning to think 'ignition' again. As I've already swapped out the coil (of the problem - vert. - cylinder), and swapped the ignitors, the only thing left that I can think of is the ignition pickup coils - so that's the next thing to try and get.
Anyway - I went for a ride (it was 30C, and too hot to do outdoors work) - yesterday - up to a friends coastal retreat. About a 400km round trip. Must suck to be sitting in snow...
Yahoo! Bastard thing. Well, I was right, it was electrical. Last time I rode it (a couple of days ago), it was getting really temperamental, and the misfire was coming and going at various revs and times - so bad at one stage I thought I was going to have to call for a pickup. Anyway, I thought I'd have a look today - thinking maybe the wires from the pickup coils were failing, causing the intermittent misfire...
So, I get the fairing side off, and pull the battery - and look at the coils, thinking - "I think I changed the horizontal coil last time - maybe I'll change the vertical again..." So trot off and grab a spare (used) coil, and I checked how tight the plug cap was on the lead - and 'pop' - and it came off in my hand. "Hmmmmm..." I wonder if that's my problem. Grab the plug cap on the vert. cylinder - and it didn't even pop - it just fell off. So out with the sidecutters, and I snipped off about 15mm (1/2") of lead, and screwed the plug caps back on (I did both plugs). Fired it up, and no misfire.
Took it for a quick ride, and it's sweet as.
Now I just need a new front tyre.
So to those who said "it's the plug leads" - you were close. The leads were OK, but the caps were as loose as hell. Just tight enough that they didn't fall off when I was pulling spark plugs out.