I think it's an adjustment but to bring the idle up, the newer john sons have that system. If you lift the tiller up on the underside is the tension adjustment for throttle.
Too old a motor to have kill cord system fitted me thinks so it's likely to be a stop button too on the tip
But don't quote me on it either...
Peter ~
askboatsandoutboards4sale@sky.com ~ 07930 421007