The valve adjustment, as well as cam chain adjustment for the Honda CB450, CL450 Scrambler, and CB500T, is part of the regular tune-up procedure. Cam chain and valve clearance should be set every 1,500 m (2,400 km). It should then be followed by ignition timing.
Parts and Tools Used:
Cam chain adjustment is easy and straightforward but if it's your first time, it will involve marking your timing rotor with the TDC position to make setting your cam chain tension easy the next time. Valve adjustment will be a bit more elaborate. From the factory, Honda sets the values for the valve clearance at 0.0012" (0.03 mm), which is too tight in our opinion, leading to worn cams and cam followers. We do an inspection of the camshaft lobes prior to adjusting the valves.
We set the valves at a looser 0.003" (0.08 mm) and get there with our overshoot method of using one size larger feeler gauge at 0.004" (0.10 mm). A tight 0.004" is close enough to a loose 0.003".
Finally, we give the cam lobes a coat of assembly lube and pre-lubricate the cam chain and the rest of the valve train components. We want to make sure there is ample lubrication upon restart.