https://www.common-motor.com/honda-350
The Honda CB350 family of two cylinder motorcycles (CB350, CL350 Scrambler, SL350) should have the engine valve clearance adjusted every 1500 miles (2400 Kilometers) as part of the standard tune-up maintenance process. However the process of adjusting the valves is a bit confusing on the CB350 engine due to its design, which is not as intuitive as in other engines. In this video we will explain in detail how the valve adjustment system works on the CB350 / CL350 / SL350 K series engine as well as showing the differences between the early and late style camshafts that appeared during the production run from 1968 to 1973. This does not apply to the CB350F (four cylinder)
Feeler Gauge Set : https://www.common-motor.com/feeler-gauge-set