Hello all. I posted a few times last summer about engine trouble. I have finally got the carburetors clean and roughly adjusted so that the bike runs fairly well. Now however, there is a rather distinctive knock coming from the bottom end when the bike is idling in neutral. When the clutch lever is pulled, the knock goes away. There is also no knock when the bike is in gear. It shifts ok and doesn't seem to slip at all. No gear whine either. PLEASE I can use a little good news. Could it possibly be something minor? 1992 with 23k. Thanks.