Thanks very much for that Andy and Stephen (pm'd you both). It will be a great help. I can see that even the smalest particle could block those very small jets with potentially fatal results !!! I kind of liked the idea of potentially having more control over fueling and the idea that sharing out the main jet like this might give better atomisation especially considering the ns cylinders most likely won't pull as hard through the bigger carbs. Allens do some very small kehin main jets that have the correct sizes and look like they will fit up there but are slightly different shape so that was a bit risky (99101-106).