thanks everyone for your responses. the real reason I want to do this is because I am building a go-kart out of this engine and I want to be able to see what the RPMs of the soon to be modified 8hp briggs. I have an old lawn tractor transaxle that I beefing up internaly. Once I get the money, I'm gonna beef up the engine with aftermarket lawn mower racing parts, port and polish the engine block, ect. My Brother-In-Law told me that when he raced Jr. dragsters as a kid, the engines were running 7000RPMs with a factory briggs 5hp engine block, crankshaft, and flywheel (the factory block was modified with a bigger piston, bigger valves, ported and polished, ect. but was still an original cast aluminum briggs and stratton block) and that was 15-20 years ago. So I'm pretty sure with the right parts I can get 7000 RPMs out of a 8hp briggs because small engine technolgy has advanced a lot in the past 15-20 years.