Mine has 41mm FCR split singles, to start it needs a couple of twists to prime the cylinders and then needs 'tickling' for a while until there's some heat in the engine otherwise it'll stop.
To help with this I fitted a 916 throttle/twistgrip which has a 'switch' that holds the throttle part open so it'll idle around 2,000 rpm.
Once warmed up they run really well, lightning fast throttle response - probably a little too 'on/off' initially but fitting a TPS to one of the carbs helped smooth it out. I think this was mostly down to the Ignitech advance being too 'keen' and having the TPS better synchronises the timing/fuelling setup.
Can be very thirsty if you've got a heavy right hand though...
