I'll second what Bob has said about melting a piston, or in my case two. A co-worker driviing his Honda 250, single carb, twin cylinder, got about 50 feet when the engine died. Teardown revealed the carb mounting bolts vibrated loose and in seconds the lean mixture put dime size holes in each piston top. With all the engine sensor pickups available with computer readouts a dyno is the only way to go for super fine tuning. The gofast big boys use telemetry sending the info of the engine to computers and the crew can send and make adjustments during the course of the race.