Motorcycle Repair: knocking, screw driver, cb750

Question
I recently bought a 91 CB750, love the bike. I changed the oil and filter when I got it, when I ride it now. I hear some knocking when I'm coasting. I recently changed the plug with NGk, at first it stop for a about 100 miles the hear the knocking again. I believe it might be the rings? or maybe the rod? I think i put to much oil? it suppose to take about 2.7L of oil i put 3L of oil. how can i fix this the knocking problem?

Answer
Bill, you need to find out where it's coming from.  Take a long screw driver and put the handle up to your ear and put the blade on various parts of the engine..cylinder, crankcase, cam housing and see where the noise is the loudest.  The screwdriver will act just like a stethoscope and you can pin point where it's coming from.  Once you know, I can give you a better idea of what you'll have to do to fix it.  You didn't put enough oil in to cause a problem so that's not it.   Are you sure it's not your drive chain?  Sometime those wear unevenly and the get tight spots which can cause a pulsing type sound when coasting.

Regards
Rich