Fuel
First, overthehill, remind me to buy you a saucer of milk next time we meet..........
I think that much of the stuff we spend our time agonising about doesn't matter a toss. The man who build my Manx Norton engine (13.8:1, Cosworth pistons £250 a pop) says that they need to be timed to 34, and if the valve timing is within 5 degrees, it's OK. I was pulling 8300, 145 mph at Chimay, no worries, no new pistons, so I believe him. The plug is best described as "dirty white". Vincents run maybe 9:1, mine runs 7:1, so just how critical do you think all this stuff is?
My policy has always been to put myself in the position of the seller. How many owners can get the mixture within 1% of perfect? The ignition timing? The valve timing?
I have a Sunbeam S7. OK, my secret shame. But mine went like **** off a shovel when I accidentally advanced the ignition timing to 40 instead of 30. It has the same cr as a Vincent , so why would it need 10 deg less advance? Because grossly underloaded it would minimise warranty claims? Tell me BSA would never do such a thing! Thus revealing yourself as a moron.
A cynic is what an idealist calls a realist.