Originally Posted by blackjackel
Thanks everyone for all your help. According to the advice i think I will roll the dice on one of them ebay motors and see what happens. If the parts break down I will purchase them one by one.
I have one more question, do they have motors where the chain is adjustible to different gears? Where I am able to "shift gears" just like i do normally do?
Perhaps some sort of mod that hooks my regular gear shifter onto the motor chain or something like that?
Is this a seperate mod? Or do I need to buy a special motor kit for that? Or will I need to purchase a whole new wheel assembly or something?
There is a mod for that. You have to start with a bike that already has gears though. Take a look at Sick Bike Parts (SBP).
Sick Bike Parts LLC - Performance parts for your motorized bicycle
I purchased their HD kit and used it with a 48cc angle fire Grubee engine. This doesn't really give me a faster top speed, the limiting factor for my speed is power. It does however let me have the fastest top speed that motor can produce (about 35mph), and it can still clime just about any hill at 15mph. With this set up 25mph is nice and comfortable. 30mph is okay, but 35mph feels like the bike is screaming and there has to be a bit of a downhill slope. I'm sure that the bike would go faster than 35mph on a good down hill run, but I don't push it any faster than that for the bikes sake as well as mine. One last thing though, this was not a "bolt on" installation with my frame and engine combination. I had to make good use of my welder and end mill to get it all to mount correctly. These things are a real kick in the pants, but you better be ready for working on it. This is especially true if you want to start adding modifications like a jack shaft shift kit. For an easy start I would first find a bike that is in good condition that is known to work with these motors. Then buy a kit and just get it running. Upgrade the cheap parts as you want/need to. If you still like playing with it and working on it, then buy a jack shaft kit. Biting off more than you can chew for your first go at it may sour you taste for the hobby.