Unless your getting old products I think all of the engines have the bearings now. If you didnt do something to mess it up (bad breakin), you just got a screwy motor ( very possible), or just bad luck I wouldnt toss the whole idea in the can. A new 2 stroke is just over a hundred bucks man. Great opportunity to learn, have fun, and solidify your understanding of the hobby. Trust me you can mess up a 4 stroke just the same as a 2
I am a newbe to this whole thing too but very mechanically inclined and very thourough in what I do. I posted a newbies experience in this market thread you may want to read. In addition to the other comments I posted the link I gave you is one distributor I forgot to mention in thepost. I did a peliminary review of them by calling ad emailing and they would of been a company i would of purchased from but they just didnt have any kits at the time. They were very helpful, knew the product, and involved in the market.
A link to that thread: http://motorbicycling.com/showthread.php?t=38018