I noticed that when i re-built my FA-72. The valves have a ton of over lap. I had an old chevy that had a pretty hot motor an when i built it i installed a cam that had alot of overlap. Now on a multi cylinder engine i can understand how it can give you an edge. But on a single cylinder saito you don't have other cylinders carring the one thats just pushed the exh out. Hey unless both valves being open makes it scavenge? I think thats when the hot gasses leaveing the cylinder sorta help pull a new charge of fuel an air in from the vacume created while the intake is open right before the exh valve closes

I really should think about these things before i start typeing, an then you guys would not have to see me answer my own question like a moron----