[bmxmon]

65 and 66 were the only years of that size rear end, it grew after 66. So either its from 65, 66, or narrowed. Check inital timing, and again vaccum leaks around the carb/intake. I had a problem before that there was another vaccum hook up on my carb and i didnt notice it, so check that out. Intakes seem to like to leak out the back where you cant see them very well, so look that over. When you time it make sure you block all your vaccum lines off. Also, when you adjust your carb keep leaning it out until it starts stumbling, then turn up the idle. Its possible your dumping too much fuel in there. Good luck, hope ya get it figured out.