This week I've noticed that the rev counter is off the scale while riding and not showing anything while on tickover.
Obviously it's working in some form or other, but other than that can anyone shed some light onto how they work and what might be wrong with it.
I do have a spare set of clocks which I could swap if the need arises, but I suspect it's not the clock that's the problem...

It is probably going to be an earthing issue - there are some earth points on the clock bracket if I am not being thick - something just loose methinks.

sounds like a bad earth or a snapped wire somewhere, if your spare set don't fix it I can drop by sometime and have a look if you want.

had a look at the earth on the back of the clock, an it was well and truly on there, not loose at all. So it's not that. Any other ideas?

I'm not 100% sure but my experiences with the tacho has been linked with the coil?
A 400 guru will be along shortly.......

If it was me and I had a spare set of known good clocks, I'd swap them over and see what happens, if it cures it you've isolated the problem to the clocks, if not you'll be looking at the rev counter pickup or the wiring in between, I'll get my nose in the haynes manual and have a look at the wiring diagram.

I'm only spitballing, but could a wonky CDI be sending a bad signal to the rev counter? I have a spare you can try out if you want to if swapping the clocks doesn't help, came from my own bike before swapping to the Ignitech.

hmmmmm.Everything else works ok, how would I know if it's a coil or CDI? Would anything else be affected?

Check the charging volts.

...on the battery with bike on tickover?

Right I've just done a quick voltage test.

The battery reads 14.3 volts.
I read up the manual, and it says to check the ohms of the coils.
This is my voltmeter. I don't know how to use it on ohms!

So I did the following:
disconnected battery
Unplugged rear coil wires and the rear HT leads
On the rear coil, the ohms between the two connectors read:
0.01 on 20k setting (as per my picture above
004 on 2,000k setting
3.6 on 200k setting

On the rear HT leads, the ohms between the leads read:
039 on 2000k setting
38.9 on 200k setting.

I haven't got time to check the fronts as the fairing and radiator will have to come off.
So, the above readings don't mean anything to me. Can anyone interpret them and tell if there's a problem with the rear coil?
Also, if it is a faulty coil, is it OK to ride my bike?