Happily broken in, my fairly new HT 66cc was performing very well, carrying my 250# self up very steep inclines and running smoothly overall, when 2 head bolt holes became stripped out. After ahell-coil repair of said holes, I proceeded to brake a piston ring during reassembly. I replaced that and was satisfied with my work, the head bolts took the necessary torque and thus I began my first ride post repair, the engine started, I released the choke & as the engine began to rev, thee was a sickening sound & the engine gasped and stopped. The piston is totally fused to the cylinder, thus far I've been unable to free it, but furthermore, the clutch seems to have failed as well, I get no repression from the motor, the wheel & chain spin freely. In other words, this particular iteration of the "riquimbly Dervish" model 3.3 is sadly gone. I have this one & 2 other complete (though disassembled) engines that I'm considering attempting to fabricobble a single working engine from. Maybe. Or maybe I'll scrap the whole thing and get a Flying Horse Bullet Train. I've heard good things. I'm frustrated with the unreliable nature of the HT, at one point tardiness due to maintenance actually cost me a job! I understand these are not motorcycles, and we're subjecting bicycle frames to forces they were never designed for, coupled with the nature of the cheap manufacture methods of the motors, lacking in any meaningful quality control, adding to all that the questionable adherence to EPA regulations and dicey, arguable legality of importing these things, none of this points to quality, reliability or consistency. Needing to keep project construction costs as low as possible, options are scarce. There are inexpensive 4 stroke options, but those are at 49cc for the most part, weighing what I do and the enormous hills I live nearby calls for greater displacement. There are the Harbor Freight 212cc 4 strokes and kits to adapt them, but at that much displacement it's just too damn close to a motorcycle, and all the insurance and registration and license headaches. Electric options are very attractive, but battery prices must come way down first. I believe that batteries are in fact becoming more affordable but they are still outside of my grasp. Whizzers, Cruzzers and the like cost far too much. I've read a lot of good things about the 2 stroke Flying Horse 66cc Bullet Train, centrifical clutch and electric start. Adding my horn, turn, brake and headlights and quite possibly a sound system seems doable on this kit. It hasn't been on the market too terribly long and I have yet to see parts and accessories available. The $300 price tag puts it way up at the higher end of possible for me. I'll take the opportunity to upgrade my fork, brakes & handlebars, but the chromoly mountain bike frame from my 1985 Fat City Cycles, "Fat Chance" model is up to the task of housing the power plant and accessories. Well this was a bit of a longer ramble than I had initially intended, sorry about that, though thanks for reading & please let me know your thoughts!