On a crazy, half-baked, fully drunken whim, I bought a 66cc, advertised as 80cc, Made-in-China Happy Time 2-stoke engine kit from bikeberry.com. The instructions were written for a tiller, in really bad pidgin translation. So, I left it alone for a month, while perusing the gas bike boards, before really getting serious about installing it on a real two-tired bike. Ha ha. After getting enough info to feel half-way comfortable, I finally finished. Thinking I just wasted a whole month, $200, $50 just for the KREEM fuel tank liner, the damn thing actually fired up and rolled! Of course, the muffler end cap fell off on the first ride. Then, after a few more rides, the quarter-inch, frame-mounting bolt snapped in two. Grade 8 5/16, fo' shure. That took another 48 hours of brutal, greasy work. Had to remount the whole engine, not just a broken bolt replacement. If you don't have a REAL sense of humor, DON'T do gas bikes. The ride ain't exactly rolls-royce. It feels more like riding a two-tired weedeater. So far, my legs are still attached firmly to my hip! Thanks for all the help, guys!