Whilst out yesterday in the +90's micro heatwave my '04 900 started to misfire badly under load.
I'd been out for a couple of hours at this point without any suggestion of a problem, then whilst tickling along the A6 for 20 mins or so in traffic I notices the odd mis, but when I tried to overtake it missed badly and wouldn't accelerate until I lifted off, at which point it picked up. If at that point I added a little throttle it would lurch and stall (not completely).
I nursed it home, whipped out the plugs to find they looked slightly lean.
The bike's done 40k but I've only had it for around 6 months and it'd not long been serviced when I got it so the plugs have only done a couple of thousand miles, although the guy who sold it told me it had hardly had any use for a couple of years.
I do remember the first time I took it for a spin it was raining and after a quick 5 mile blat up the local test track (A675) I noticed it missed and hesitated as I backed off the tap. I put it down to the leads and expected to have to change them somewhere in the near future but since then almost nothing until yesterday.
Has anyone any idea what this could be? a common thing maybe? Fuelling issue possibly?
Any help or pointers are always appreciated (especially when it's 90° outside)