Did you re-synchronized the carburetors?

So have it all back together and it's worse than before now... What have I done!!! If I put the plugs to earth on the crank case the spark is fantastic.. But resting the plug anywhere on the cylinder and there is no spark or a very weak one... Is the right??? Could there be a poor earth to the cylinders ??? Clutching at straws here!!!!

Quote from KINGPRAWN on 10.12.13 at 12:18:49:


The butterfly valves must both be completely closed and then they MUST OPEN SIMULTANEOUSLY, when put into action. This is important. Otherwise the engine will not start at all or will be running on only one cylinder. This backfiring is a typical effect.

Hang on,

Stefan

  SHE PURS LIKE A KITTEN AND ROARS LIKE A LION  

I have had exactly the same problems I tried carb cleaning ,new plugs ,caps etc got a reasonable result with a change of front coil but still not right ,you could grab hold of the front downpipe but you could hear it try to pop in every now and then and fuel dripping from exhaust etc .As a last resort before suicide I took the carbs off again I bought nrp keyster kits which are different for the front and rear cylinder I know the jets are different but I was also wondering if the needles were as well, but heres the crux when checking the needles I noticed more up down movement within the needle itself on the front pot ,the needles are held in place by a plastic allan bolt which contains a spring which presses down upon the needle, upon replacement of all parts far less /almost none ,movement within said spring and needle so I was guessing this was a major part of the problem as now both pots run hot although mine are still a bit rich but that could be down to the predator exhaust pipe ,hope this helps ,good luck