Managed to drain the fuel from the carbs and turning it upside down and removing the covers I can see the mains and pilot jets. I replaced the mains (115 in the front and 118 in the rear) for 120's all round, courtesy of CMS, Exeter. Also, gave the pilots 2 x 180 degree turns (or half turns) out from tight. Manual says 2.25 turns out but that makes them loose enough to rattle out on vibration? Anyway, started it up and it revs smooth right up to 10k. Hopefully a road test soon!