Ok, so about 18 months ago, I stripped and cleaned my carbs and replaced the o-rings. Everything seemed fine, and it appeared to have solved the problem at the third attempt.
I then stupidly let the bike sit for said 18months, until I tried to run it up today. It starts and idles fine, but will now bog down and/or stall with any throttle. Can anybody suggest a reason why it's doing this, and any possible fixes, as I'm booked in for a trackday in 10 days time, and it's going to be cutting it close to get it ready.

Try draining the float bowls then use the "Prime" setting to fill them back up again. Also give it a good blast to clear it out...

Ok, tried to get it going today.
I took the carbs out, cleaned them and tried again to no avail. Bike idled nice and evenly, definitely running on 4 cylinders. However, with any throttle, it still bogged down, stumbles then revs up a bit but won't pass 6k revs.

So I took them out again and put new BS010's on the jets just to be sure that it's not leaking through. When I get back from work tomorrow, i'll chuck them back in the bike and see if things improve.

I wonder if anybody has a good photo of the BS010's in place? They're really fat and don't go all the way into the body of the carb. Maybe i'm fitting them wrong?

If not, can anybody suggest any other reason why the bike won't rev?

The BS010's are imperial fitting and are too big Tony stuck larger o'rings in his gsxr to try and get a tight fit.
New o'rings will fit fine without being oversize.
I'd have a good look at the main air jets as it sounds like its running rich as you open the throttle.

Just bumping this thread to see if anybody can help. I've replaced all the O-rings with VVS's kit, but it still seems to be running rich, with a little white smoke from the exhaust.
I've run out of ideas as to what's gone wrong, can anybody help?

Try winding the pilot air screws out a 1/8 turn. That should lean down the mixture a bit, it'll increase the air flow.