Max-torque is the route for a cheap china clone pred engine!
12/60 worked great on my Fimco, racing on the slightly less than 1/8 mile indoor oval last weekend. It jumped off the line and still had good top end speed w/lightly modded 212 Predator, no governor, 4.10 x 3.50 -6 tires, 120 lb rider. We won the race going away.
Now I'm building up my old Ruttman for a larger outdoor track. The race line around the Castle Rock, Wash., oval is a bit over 1,400 feet long, or 1/4+ mile. The corners are broad and it should be possible to go flat out just about all the way 'round with a good rider. Bike will have 6" wheels, no jackshaft, an engine w/similar mods to the Fimco, and a light weight rider. Taller gearing will be in order, but I'm not sure if I want to get a TAV. I can just pop on a new clutch w/bigger sprocket and not have to mess w/rear sprocket (60T), and retain the clutch brake. 13T-15T on the front gives a ratio range of 4.6 - 4.0. Do you think that I'll toast the clutch? It only needs to last one race day, perhaps three 6-lap sessions (practice, heat race, and main event).