As TNP says there is an L shaped pressed steel lever centre pivoted on a
governor pin near the sump (bottom of engine)
This has a spring on the shorter arm to the engine and a wire linkage to the
carb' on the longer arm with a fine spring over the linkage .This linkage
should hold the throttle fully open and close it as the engine revs.
Normally the bolt securing the arm works loose and the governor shaft turns
without moving the linkage.
Remove the air filter and see if the butterfly valve is open in the carb' if
not adjust the linkage the shaft should have a slot in it for a screwdriver.

HTH

CJ