So, after a very nice rebuild on a 78 650, with new everything, Im riding down I-5 in 5th gear and I feel a clunk in the gear box. Oh no. Then Im on ride with a group and the same thing happens. 5th gear running about 65 and a clunk worse than the first. ANYONE HAD THIS HAPPEN TO THEM?. If so, what the heck is going on?. I dropped the pan and no metal in the oil. Looked up inside the cases and everything seems in tact. Hmmmmm. Any one?