Small Engines (Lawn Mowers, etc.): small engine, head gasket, valve adjustments

Question
mr.jones i recently bought one of those clone motors from harbour freight. we un governed it but we want to make them fast, last longer and try and stay in the affordable range. no more than 100 dollars to spend. see we race in a field beside our house its a 1/8 mile flat dirt track with a figure 8 so its all for fun but we want more speed any suggestions

Answer
Probably the best use of the money is upgrading the air cleaner set-up to one of the perfomance ones.  The ones made for Honda should be the simplest to adapt.  Without much money, the air cleaner and the exhaust is where I'd put my cash.  You could tighten up the valve adjustments a little and the head would benefit from some port and polish work, you'd need a book to guide you through that if you haven't done anything like this before.  A thinner head gasket will boost compression and advancing the timing a little will help take advantage of the modifications.

For longevity, about all you can really do is tear it down and balance the rotating assembly and use high quality oil.  I prefer Castrol myself.  Change it regularly and monitor it for metal and burning.

These are pretty decent engines and I know a lot of the racers are using them, or at least the blocks, for build-ups.  A lot of Honda parts work on them.  Thanks, PK.