Thriumph TR6R 1967 I was adjusting my back brake today with the bike on the main stand, in neutral, and noticed that when I turn of the back wheel in the forward direction there is a light knocking sound from the gearbox. For every turn of the rear wheel there are approx three knocks. It sounds like knocking one's knuckle on a wooden box. Not very loud. It doesn't do it if I rotate the wheel backwards. What could this be? I tried taking the slack out and also moving the chain sideways with my other hand as I turned but it still did it. Could it be a tooth on the gearbox sprocket, loose gearbox sprocket or maybe a high gear tooth?
With the bike on the center stand lean it over to the left and turn the rear wheel. If it still makes a knocking noise lean the bike over to the right and turn the wheel, is the noise still there? If the noise goes away you might have a shifter fork ring that has somehow fallen off the shifter fork. This usually happens upon assembling the transmission and it's not noticed until the rider detects a sloppy shifting issue and or a noise like you are hearing. If the knocking doesn't go away you have other issues.
I went back out to the bike later when it had cooled down and it didn't do it anymore. I wonder if it is some clearance problem somewhere. I suspect that it may have always done this without me noticing. When I lube the chain when the bike is still hot after a run I spin the wheel backwards so wouldn't notice it! Also, I tend to normally check the brakes when the bike is cold. Will check into this again during the week.
Whatley How do you remember all this stuff? I just found my copy of Healy's "Tech tips". At least 35 years old, spiral bound, a lot of it eligible due to the poor copying technology of the day. And you were a contributor.
1968 T120R 1972 T120RV Any advice given is without a warranty expressed or implied.
Been doing this way too long ! I was the tech editor for the TOMCC mag Nacelle in the mid-70's. I had to laugh. Something about the Brits sending their questions about their Brit motorcycles to the USA for answers.