Small Engines (Lawn Mowers, etc.): tuning and turning my lawn mower in a mud bogger / go cart, brigs and stratton, stroke engine

Question
Hello,

i am tuning my lawn mower in the weekends but i am stuck on the question : how can i make it faster without opening the engine?. it has a 13 hp brigs and stratton vertical driveshaft motor. I read in an article somewhere else you can mount a larger pully in the front and a smaller one in the back. i was thinking of a bike technique .. is it possible to use the chain and sprokkets of a bike ? or wil it colapse at high rpm's? and what COULD i do to make it faster by adding simple techniques? i already cut a hacked away al unecercerly parts. my last question si if i could turn my vertical drivershaft in a horizontal witout tuning the 2 stroke engine?

thanks allot and sorry for my bad english

Answer
I wouldn't recommend speeding up the pulley speed going into the transmission because it was not designed to operate and lubricate correctly at higher RPM levels.  If you need a horizontal engine, I recommend getting one because the time and parts required to change a vertical to a horizontal makes the proposition more expensive.  Hope this helps.