Originally Posted by disston
As mentioned earlier. The Bing carbs all have a different start position on the mix screw. From this position the bike can be riden enough to warm up and then a final adjustment of the carbs performed. Also mentioned earlier the tune up should include a valve adjustment first, then points dwell and timing (new plugs often are helpful. Then the carbs can be adjusted.
Those carbs are the stock crabs for all R90/6 machines. The start setting for the mixture screw is One (1) full turn out. BTW this is a fuel adjustment, not an air adjustment like in many carbs. Counter clockwise is richer.
Thanks for the notes. I'm awaiting delivy of the points and condenser. Did the valves tonight ( were a bit tight). Also obtained coils, plug wires, and new spark plugs. This weekend I'll install all the new parts and see if I can get it back to running like it was. ( also ordered a new nutral switch and will install it too due to leaks). Another few years of r90/6 ownership and I may know something about working on one. :)
Ps: yes, have an old shop manual that came with the bike.