Ok folks if you will do your best to think what this might be I would be obliged. Took the bike out yesterday ran well and had a lot of fun right up till it started to fart and misfire, checked the plugs (ok) checked fuel lines(ok) was stopped on the side of the road swearing at it and it would not start, then out of nowhere it fired right up but not firing on number 4 cylinder. is it possible for one side of the coil pack to break? Fiddled with the HT cable and found it had a spark but still would not fire so decided to ride it home anyway and sod the damage it might do, half a mile down the road it fired up and went like nothing was wrong, the only other thing I had done was turn the fuel tap to reserve!! Oh and when it first behaved badly I had just passed a little sports car at about 80 so was also wondering if coil pack can break down with heat/stress? Any thoughts on what might be the problem would be appreciated as I am stumped, by the way this is NOT the first time it has done this (misfired) but the first time it has actually ground to a halt, first time was on the M5 at a steady 75 for a couple of hours. Thanks all.