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 1500 miles (2500KM).
Parts and Tools Used:
Feeler gauge set: http://www.common-motor.com/feeler-gauge-set
Honda CB450 Service Gasket Set: http://www.common-motor.com/honda-450-service-gaskets
Cam Chain adjustment is easy and straight forward. While the valve adjustment is a bit more elaborate.
From the factory Honda values for the valve clearance at 0.0012" (0.03 mm), which is too tight in our opinion, leading to worn cams and cam follower. We do and inspection 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.