I say hello here, and ill tell my story. a year or so ago my brother was trying to make a motorized bike from a weed wacker, but he eventually gave it up. I had heard about people selling 66/80cc kits online, but didn't get one until about a month ago. I unpacked the kit, a "simple" one by seuutek, bought from ebay, assemble it in 3 hours, then a bit of tuning and general messing around with the thing. My biggest mistake was over torquing one head bolt a few days later. I then got a 5/16th heli-coil kit to repair the motor, ending up doing all 4 for safety. it ran for a few more days, but not before i found a guy selling a bike, one that had not run in a couple years, but for the price of $125. The bike itself is an old style beach cruiser, something i have had my eye on for awhile. When i put the first kit together, it was put on an old mongoose mountain bike, being the only one big enough to fit the motor on. now, after getting and riding this new bike, i believe it is a rather used one, but has plenty of compression left. after i fixed the first motor, it ran for awhile but has began to leak again, with about 75 miles on the motor now. When it began to leak again, i focused on this new-old bike, tightening this, straightening that, then: I was riding along at maybe 10 miles an hour, the chain tension-er, the bottom bolt to be exact, i must have stripped the buttery bolt, because it came loose, leaned right into the tire, and threw me about 10 feet in front and to the right of my bike... After that happened, it has been one little thing after another, the plug on the spark plug, the grip (or whatever its called) broke off, (fixable in time) so i used the new cdi w/ spark plug wire off the other bike, when the chain tension-er threw me, it snapped the masterlink on the chain as well (gonna get another from ace hardware or online) the carb started screwing up, going full throttle and getting stuck at full (not good if you wanna stop...) found out its that little pin, the REALLY tiny one, that holds the throttle thingy straight in the carb so the idle screw is aligned(you can tell i don't know the lingo) the last but not least, between the muffler and the pipe (is that what it is called???) from the motor, these two pieces seem to have rusted/broke/wore down and snapped off... replaced with spare muffler... just many small things that wore down. the previous owner of the bike had lost his license for i don't know how long, and used this to get everywhere, so it must have a good amount of miles on it. one major thing i have found, is i replaced the cheap air filter with a good lawn mower foam piece, motor runs smoother now. Is it good to use an expansion chamber? that is one of the major upgrades to do eventually. I plan to use, and possibly build and sell these bikes in the future. they are really cool. Thanks for taking the time to read this, now i will go digging in this great forum of a gold mine for more ideas!!! EDIT: I am editing already... I am going to build a small trailer for my bike, don't know how much weight it would be. I will definately be on road only. anyone have pointers on trailers??? i cant find much info on them.