Small Engines (Lawn Mowers, etc.): lawn mowers, clearence, lawn mower

Question
im making a racing lawn mower i was wondering how i can make a stock lawn mower go farlly fast with out changing the motor. thanks Jay

Answer
Hi Jay,

You could mill a little off the bottom of the head to increase the compression.  I don't have specs so you would need to proceed with caution, especially watching the clearence for the valves. Change the muffler to reduce back pressure. Remove the air filter to allow more air, with an adjustment to the carb for more fuel.  Advance the spark.  These are things that I have heard of over the years but I don't have specific info to tell you how much of each.

A search pulled up the following.  It may or may not have useful info for you:
http://www.briggsracing.com/gettingstarted.html

Good Luck,
Michael