I have measured the output shaft on the 4g and of course it is not a nice easy 5/8". For all you guys who all ready have a 4G and your chain sprocket is where you want your pulley to be, our builds will be a little different. My pulley needs to be as close as possible to the trasmission housing and even then I might have to offset the whole motor a little to get the pulley lined up with the rear sheave. I don't know if my motor case is different or what. The part of the output shaft that I will be putting the pulley on is just under 5/8", the part where the one way sprocket is mounted is much smaller. I will have to do a little build up with Jb weld and then sand back down to 5/8". One good side effect of where I am placing the pulley on the shaft is there will be a lot less stress on the shaft than way out there where the stock sprocket is.
McMaster-Carr has a ton of pulleys and belts available and mine was shipped immediately. I got the 3.5" OD with a 5/8" bore, which is keyed + set screw. The thing is built like a tank, made for serious factory work. It is very heavy cast iron, I would prefer aluminum but at least I don't need to worry about it ever giving up on me.
The adjustable pulleys are a neat idea but a lot more expensive. At this point I am trying to fit the largest possible pulley in there so being able to adjust it smaller didn't seem like an advantage worth paying for.
The bike is being put on hold for a few weeks. My mom is getting older and crashed her car into a tree for no apparent reason. She's fine but the car needs a ton of work. The insurance company totalled it but since it only has 22k miles I bought it back from them to repair. I will be replacing the whole front bumper, hood, fender, headlight, maybe radiator and getting all the mounting points bent back into place... frame looks good and i was able to drive it back to my place with no weirdness in the drivetrain. On the other hand I could get the bike fixed up and let mom ride that, at least she won't kill anybody if she crashes into them.
SOOOOooo. Off to Ace Hwd for plan B. I bought a 5/8 heavy steel spacer. Drilled it out to the diameter of the small stepped bit of the shaft. 27/64 ths bit worked well. For the machiensts in the audience. Turn away now and DONT look at the pictures... To cut a keyway for the pulley I used my Dremel and a cutoff wheel to carefully carve away the offending metal. I previously marked the bit to be removed with a sharpy. Great care must be taken and bracing yourself helps alot to keep the cut nice and streight. Those who have ever worked clay on a Throwing wheel know of what I speak. Next came the inner keyway for the tiny key in the skinny part of the shaft. For this I chose a carbide carving bit
