hello all. I am new to this forum and need a little advice. I recently purchased a custom bike that was very poorly assembled. i am a mechanic but new to bikes. i rode it about 3 times then stripped it down to the engine, trans & frame. the bike has a 96 softail engine, 5 speed trans and rear fender, everything else is aftermarket. i have fixed many of the bikes problems but have hit a roadblock. the problem i'm having is with the drive belt trying to climb off the inner edge of the pulley, well not literally but it rubs it and makes a popping sound no matter which direction the wheel is turned. i have spaced the wheel as far to the brake side as i can and it still does it. the pulley has a .250" back spacer. i thought it might be too thick so using washers i mocked it up at .200" (the most common size i saw as available on the web) but that didn't make a difference. i then mocked it up at .125" but then it was too thin and the belt rubbed on the tire. and yes i have made sure the wheel is aligned. i used a piece of welding rod with a small zip tie on it to make sure the distance from the swing arm bolt and the axle were equal. so i'm thinking maybe the trans isn't aligned properly causing the drive belt to track to the inside. oh yeah, rear tire is 180/70x16.
any thoughts? and how do i correct? please help!
thanks

 

Unbolt the transmission and allow it to settle where it will, then check your rear wheel alignment, space as necessary then tighten down the trans. Some of the aftermarket frames out there didn't have the best tolerances and the holes in the trans plate may have not been drilled properly.