pretty sure that the only way an a series "governs" (i use that term loosly) is that it either
runs out of fuel/air mix
dizzy breaks down at high rpm

The engine doesent have a governer a such, just engine limitations.

One the two forklifts i have looked at (both had toytoa engines) they just had a throttle screw to set the engine speed. i guess you could call that a goverener of sorts.