Here's the deal... Anything that comes out of a can isn't going to be as durable as a 2 part mix you spray from a gun. This goes for primer as well. There are good rattle can products out there that do work and bond well, but they will never be AS good as a 2 part mix. The activator, or hardner, that is used with most automotive clear coats, primers and single stage paints creates a chemical reaction that not only cures the product, but also makes it hard and resistant against chemicals and fuel. This is the main reason why I don't recommend rattle can on motorcycle body parts. It's very easy to spill fuel when filling up, fork seals will eventually leak and hot engine oil is going to eventually leak all over your chassis. Any and all of these will attack a rattle can paint job. For example, when I painted the Blackhawk, I sprayed the frame and swing arm with 4 coats of clear and the tank and fender have about 10 coats of clear, factory standard is 2 coats. The reason I did that is because I planned on riding the hell out of the bike and knew it leaked a lot of oil and that I would be riding in dirt a lot. The extra coats of clear do 2 things; 1 - It makes it even more resistant to fuel spills and oily messes. 2 - If any scratches or damage were done to paint job, I would have plenty of clear coat left over to wet sand and polish out the damage.
So in short, if you want to do it really right and not have issues down the road, get yourself a small compressor and a paint gun. Even a cheaper one will give you better results than a rattle can and last longer. If this just isn't possible, then try and get base coat mixed and filled into a rattle can and use something like the that 2 part mixable spray can clear you spoke of.
If you do have to use rattle can products I highly recommend the use of SEM or UPOL products. Both are more expensive than your hardware brand stuff, but both of these products are manufactured for automotive use. ALWAYS READ AND FOLLOW THE INSTRUCTIONS CLOSELY!!!
Scottie J