Re: Need help with some direction.
Barleyawake makes some really good points. I mentioned the rear hub flange because the first bike I was going to motorize had this problem, but barelyawake is right, I have never seen a low end bike with the hub size problem. They all seem to use the standard size hub.
As far as your question about how to know if it is a quality bike or if it is a good deal, it depends what type of bike you want. I don't know much about cruisers, infact cruisers are so simple I would agree with barelyawake that a huffy will work just fine. I am into mountain bikes. I was an avid mountain biker before I discovered motorized bikes. When I look for a mountain bike to motorize I look for several things.
The first and foremost is that it is a chromolly frame (steel). Steel is better than aluminum because the tube diameters are smaller so the engine will mount easier, also steel frames dampen road and engine vibrations better than aluminum.
Second I look for specific brands. My favorite is Specialized and preferably the stumpjumper model. Other good brands are Trek and Raleigh. There are others but I have only had these three brands.
Third I look for welds, cracks, rust. If the bike looks like it is stored outside then pass on it. There should be very little rust and the rubber should be good.
Fourth, the obvious, the engine will fit and wheels are 36 spoke with the right size hub flange. Generally I have found a 19" and up frame will work.
I just found a mid 90's specialized stumpjumper in very good shape and paid 150 for it off of craigslist.
I built a cruiser for a freind and they are more comfortable but my mountain bikes feel way more solid. The mountain bike feels more like it was made for the engine and less like a toy. Also you can go offroad if you feel like it. I don't mean to offend anyone here that has cruisers. I have seen some awesome cruiser builds on here.
What type of bike were you thinking?