I had the baulking this morning while pulling away from the lights. The bike had only just started so was not hot. I had to give the throttle small blips just keep the engine going. I managed to get across the junction. When I turned on the reserve tap the problem cleared. The tank is pretty full so I assume it's a supply issue with the main fuel feed.
I think I've nailed this issue. Last week I removed the Toot, (carburettor) to make sure it was not leaking and causing a surging at moderate revs that I was getting. During the refitting of the carb I rerouted the fuel pipes to try to get a smoother run. The pipe on the float side has always been a little too short. Looking at it today I could see that the pipe had a sharp bend at the float chamber stub. I've wandered up to my local car part suppliers and bought some new fabric covered rubber fuel pipe, (same as I had before) and changed that pipe, using a slightly longer run with gentle bends. I'm hoping that the surging was also the fault of that bend in the pipe causing fuel starvation.