Well, the Chinese 2-strokes are cheaper than the 4-strokes but less reliable. They pretty much always need tweaking and fixing. The 4-strokes have problems with their centrifugal clutch and transfer case but are overall more trustworthy. The best 4-stroke setup will cost you about $650 (contact Azbill). The next best will be around $400 ( 49cc Complete Gas Powered Engine Kit - $369.99
). My understanding from reading the forum is that these kits are fairly reliable as long as you don't use the dis-engager. Jet engines, rubber bands, and various other interesting to questionable ideas can be found in the do-it-yourself section of the forum. Good luck!
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