Right I think I've sorting fixed it lol I tried the battery and put my car battery on it as well and there was no difference so I thought it could be the new plug I put in it so I put the old plug back in the bike and its been fine ever since but sometimes when i rev it and the revs die it seems to back fire but only on that cylinder ? It's certainly better with the old plug back in it and it doesn't seem to be going on to one cylinder anymore ! So I can only guess that the new plug I put in it was a duff one ?? Looks like I going to have to put another brand new plug in it and see what that does.

I've just had another thought when I took the new plug out of it it seemed to be very wet now I know this could be because it wasn't running right on the cylinder but now I've put the old plug back in, it seems to be ok but still not 100 percent and its backfiring on run over so my thought is is it overfueling on that cylinder which is causing the plug to foul and then not sparking right ? Just a thought, is there a way to tell if its overfueling ? Should of bought a four stroke lol