I need a bit of advice on where to start looking (fairly rubbish at electrics).
First the symptoms, Racing at three sisters yesterday in the Forgotten Era, one and a half laps to go with a fair lead then just open the throttle coming off the brakes, NOTHING! I pull the clutch in and am about to stop when I decided to let the clutch out and it starts fine! I rejoin and finish third. I checked a couple of connections but being a wuss I didn't want to take too much off in the paddock.
The next race it was running well at a good (for me) pace then after about 5 laps it started misfiring (more a stumble really) right through the rev range, probably only enough to lose me a second or two a lap but I was constantly waiting for it to stop. Got second though
I'm thinking it'll be electrical, only because the engine initially stopped dead in the first race.
So, today I'm thinking, airbox off, clean the carbs (because they'll be off) check the plugs first for a clue in case it's the coils or leads, check all connections and fuses.
Other than that I dont know where to look.
Any ideas? I've got the last two rounds of the championship in 4 weeks time and I dont want any problems....
Cheers all!

Sounds like failing coils. Have you considered a stick coil conversion? I think you can get away with that mod in FE

I agree, was thinking breaking down with temperature going up might be a possibility.
I'll look into the stick coil conversion, I'm sure it's been covered.
Ta!

My old Ninja 250 did that and it turned out that the connectors on the coils were loose. Since it's intermittent, I'd go over all connectors and harnesses and see if any feel loose or if you can make it die by wiggling them before you start replacing stuff at random.

Also, there are two coils. It seems unlikely they would both decide to shut down at the same time which would need to happen for the engine to totally die. It seems to point towards a single point of failure instead.

Good advice. I've decided to go for a race loom, all new wire and connectors eliminating any duff connectors on the old loom, hopefully my friend will be able to fit it in to his busy schedule! I wondered about the total shutdown too and on reflection I can't swear that it didn't just go on to two cylinders but I certainly take your point.
So far, all I've found is a loose carb rubber clamp on number 2 cylinder. cant see that being my problem though...
Cheers

Was it electrical? I was just thinking it may be a blocked breather on the fuel cap.... Had that on mine when I changed it for an NC30 one before a dyno run. NC30 has a seperate tank breather!

Looks like it was the coil, I replaced them both and made up a race loom. All good now!
Thanks all for the help.