1 cyl /2cyl 1cyl ?

[rahferret]

Started to alternate between 1 and 2 cyl, checked with air box off and could see erratic firing on front cyl, ie flame through inlet valves, cyl head off lap valve seats, new valve seals, reassemble, new head gasket, double check timing and valve clearances, quick visual on carbs and put back together, blocked vac tube, set aux fuel supply and start, still bloody doing it, will run on both then drop to single for about 10 secs then a carb fart and running on 2 for a couple of secs then back to 1. Any ideas as what to go for next.

[Watty]

Electrical!? R/R, Coils etc! Swap coils and see if issue moves to other cylinder!! Or simply dodgy plug!

[rahferret]

Strong spark from both plugs, not burning oil or petrol in oil, (rings OK) Going down carb route, strip, clean and fit inline filters, if it works i'll let you know.