I have a TS Magna stock as a rock with a #2 spark plug which missfires a lot. I checked the other plugs and they are all showing good burn qualities. #2 is a sooty black with the exception of about 1mm of the centre electrode and 1mm of the earth electrode. Change the plug I hear you all say, but what may be causing the problem apart from the plug? Or lead?

further to my post, under moderate acceleration, it backfires or detonates into the exhaust system.

number 2 valves must be leaking

to conferm use a leekdown tester will tell straight away