alskee,
The secret a lot of good welders don't want to tell anyone is that for the most part it's far less skill than it is knowledge that makes a good weld/welder.
The quality of your welds depends more on the quality of your equipment and your knowledge than it does on what you do with your hands. Most people have more than the required coordination and skill, but don't have the equipment or the knowledge of what materials to use.
TIG welding takes a few days to learn torch handling, feeding the filler and operating the pedal. It takes years to learn what settings work best on a particular project and what filler material, and how to grind the tungsten etc.
By far the cheapeast most versatile welding kit you can get would be a oxy/act gas setup. Problem is...that's the setup that also takes the most skill. With the right tip, the right gas pressure and the right filler rod you'll be gas welding steel pretty well rather quickly. Old time pro's can do aluminun with Oxy/Act....I've never developed that art myself. With gas you can weld, braze, cut, heat, bend, do all kinds of things.
For aluminum...well in my opinion you have to use TIG, and the quality of the welds will be related to the quality of your equipment. Yes, experienced welders can make due with inferior equipment, but it takes years to get to that point.
My advice would be to start with a gas outfit, get a book on gas welding and practice a lot. Gas welding can be done slowly and in a controlled manner that's easier for a beginner to cope with. Arc/TIG/MIG makes things happen fast, and can be frustrating to both handle the equipment and the fundementals of welding at the same time. A gas outfit is easy to understand...fire gets things hot, move the fire away, things get less hot. Gas wins hands down when it comes to cost and versatility. I've got two MIGs, one TIG and a gas setup...I don't use the gas much, only because it's slower. But it will do almost everything the other machines will do, and in expert hands it will do more.
Frank C. has probably forgotten more about gas welding than anyone here will ever know. He'd be a good person to talk to. In general, all I can say for motorcycle work would be to get small torches, easier to handle and control and most of the bike related stuff you will be doing won't require a lot of heat.
JohnnyB