Briggs & Stratton engines are common on lawn mowers and go-karts. The engines are sold with the most restricted RPM settings. By modifying your Briggs & Stratton engine into a racing type, you will void the engine warranty, but you will end up having a small racing engine. You will need to check a few things on the engine and remove the speed restrictive governor from the engine to make it run at its highest possible speeds.
Things You'll Need
Socket wrench and socket set
92 octane gas
Remove the flywheel shroud cover from the top of the Briggs & Stratton engine to access the flywheel and the governor bolted next to it. Use the appropriate-sized sockets to unscrew the bolts around the perimeter of the engine flywheel shroud.
Locate the governor bolted next to the flywheel via a single bolt. The governor is a small square flap next to the flywheel. Unscrew the bolt holding the flap to the engine block with the appropriate-sized socket.
Unhook the springs attached to the governor from the throttle linkage and carburetor eyelets.
Replace the flywheel shroud and bolt it into place.
Locate the muffler mounted onto the exhaust port on the side of the Briggs & Stratton engine block. Inspect the muffler for any cracks. Shake the muffler to make sure it is securely bolted to the engine block. The muffler provides back pressure to the engine that increases the engine's horsepower. Verify that the muffler is crack-free and set tightly against the engine block. Replace the muffler if it has cracks; new small engine mufflers cost around $15. The muffler simply bolts onto the engine block via two bolts.
Unscrew the bolt holding the air filter cover over the air filter. Pull out the old air filter and replace it with a new one. Racing engines need very clean air filters for optimal air intake.
Fill the gas tank with a fast-burning 92 octane fuel.