one plug looks rich ,one plug looks lean, bike runs fine

Duh I have moonshine if I want to slow thoughts down to catch some - so likely whats happening more that DS drag bending crank to load L jug more is one side is almost always firing first so get an extra combustion tan more than the other. Might play with float levels to get both sides w same pilot jet turns out then bump the lean side up or rich side down or both to see what happens. Some cycles like air coolled Vtwins can run different mixture, ignition timeing and plug heat range, so why not Norton with DS of engine hanging into breeze a bit more than TS.