Honda's engineers have a penchant for doing things differently on each model. This despite a marked similarly of design amongst the 70s SOHC fours that extends to recognizable continuity in ignition and carburetor specification. Honda seems to have encouraged variation in some design areas. Thus virtually every 70s four has a different cam chain tensioner.

The cam chain tensioner arrangement on the 1972 through 1974 CB350F and its later 6-speed iteration the 1975 through 1977 CB400F was new on the CB350F. However, in 1974 Honda introduced the CB360 twin, and it got the same tensioner design whose parts look identical but have unique part numbers. It's an interesting design. A spring-loaded rod found at the front of the engine exerts force on the familiar tensioner blade at the back of the engine via a newly-introduced horseshoe-shaped lever beneath the crankshaft. Evidentally Honda thought this somehow better than the simple rack and pinion cam chain tensioner on the CB500 Four unveiled the previous year.

History however has shown that the public--including mechanics--are confused about how the system works, if the condition of the tensioning mechanism as found on almost any example of the three models that employ it is any indication. Rarely is the tensioner on a CB350F, CB400F or CB/CL360 twin not seriously molested, often to the point of broken off hardware necessitating separation of the engine cases to repair.

The correct procedure is to remove the bolt serving as a sealing plug on the plunger. Then put the crankshaft at TDCC (compression) on the #4 cylinder. Insert a Phillips screwdriver into the hole the plunger resides in and while pushing with moderate pressure, loosen the tensioner locknut and lockbolt, rotate the crankshaft 10 to 15 degrees, and snug the lockbolt and locknut. Release pressure on the plunger and replace its sealing bolt. This is the correct way for the CB350F, CB400F and CB/CL360. Don't use any method that includes running the engine.