Hi maxcaddy, i had a little look at my bike today, and i think it is the choke plungers causing the issue, as the choke cable itself doesnt look to be engaging/dis-engaging fully all the time, which would also explain the randomness of it. I have ordered a new choke cable which i intend on fitting this weekend seeing as im doing a few bits to it this weekend, (new seals in the calipers and SS brake lines) so ill post again letting you know if this sorts the issue.
As for 'shotgunning' the carbs, it doesnt sound like a brilliant idea IMO, but i could be wrong. If you choose to follow it as a potential remedy, then thats your choice, but if you end up having more of a real life shotgun effect on them, then i think you are gonna be somewhat worse off
