I read an interesting article on pinking recently. Apparently the fundamental problem is a 'hot spot' somewhere in the combustion chamber. The effect of this is to create two points of ignition, one is the spark plug, the other is the 'hot spot'. The article stated that the pinking is caused by the two combustion pressure waves colliding. I had always thought that the pinking was simply evidence of pre-ignition i.e. the spark firing too early and the pressure wave smacking the top of the piston too soon. The most likely source of a hot spot in the cylinder head is the edges of the exhaust valves or the plug tip. Setting theory to one side for a minute I have a Super Rocket which has been plagued with pinking ever since I built it. I have tried everything! Lower compression pistons, retarded ignition, richer mixture, all of which had only minimal effect. However I recently fitted a Mikuni carb which made a big difference and cured the pinking, though I am still running the low comp pistons. The carb is set up for a Super Rocket, which the bike is no more because of the pistons. I can only deduce that the mixture provided by the Mikuni is keeping the top end a lot cooler than previously. The bike runs great in its current configuration. I have another Super Rocket spec bike which runs absolutely fine in standard SR trim. I also have two iron head A10's which both run great. My guess is that the issue with my rogue Super Rocket is the alloy head - something just ain't quite right about it! This particular cylinder head was professionally built so I have been reluctant to blame it. One day I'll return the rogue SR back to its standard trim with a different head to see how much difference it makes. Food for thought.