[embee]

2 coils, one each cylinder, pretty sure the rev counter comes off the front one (?). Follow the HT plug lead back and you'll find it. Look at both while you're in there anyway, make sure it's all clean and electrical connections are sound.

If as you say the odometer is also playing up then there's probably more to it. The curvey has a couple of well known wiring chafing points to check, any of them can cause intermittent misfires and blowing fuses etc.

Check carefully behind both the bolts holding the riders seat on, remove the black triangles first to get to them. The wiring sits right behind where the seat bolts are.
Under the pillion seat, look in the cubby area towards the rear on the left side of the bike (i.e. the chain side). The wiring bends round a frame bracket and can wear through.
The other area is generally around the headstock where the harness flexes as you turn the bars, just have a close inspection.