My Experience

I had been a lover of dirt bikes (MX bikes) for decades  but had never really studied the intricacies of how 2 strokes worked. Being an American now living in South America I needed transportation but couldn't get a license. A local business installs 48cc Grubee engines for $250 so I jumped at the chance since they don't require registration or a license to drive. I live high in the Andes mountains and was sorely disappointed at the bikes inability to climb hills. Also the thin air here has 27% less oxygen which robs the engine of power. So I set myself to understand the fine art of 2 stroke tuning and how to do modifications for power. I found out that piston port engines are best fitted for high rpm use since the intake charge gets pushed back out the intake manifold at lower rpm's. So I decided to make and install my own reed valve. Without knowing the importance of crankcase compression ratio I made the fortunate decision to install it inside the intake tract which is much better than having it before the intake manifold which would allow more crankcase space and a worse CC ratio. It broadened the powerband and gave it more power (partly from improving the CC ratio) but was still lacking. So I decided to upgrade to a 55cc engine (which bolted right on). There truly is no substitute for cubic centimeters. From there I experimented with porting and other things which are mentioned on this site until I got the kind of power I was hoping for. Now I go up the hills almost at full speed although before I couldn't climb them at all.

This has truly been a great learning experience and I hope you can benefit from what I've learned. Don't be afraid to make the same radical changes I have. In the end you'll find that you have changed for the better along with your engine.