My mower is revving to high

[blackleafy]

Does anyone know why my mower is revving to high, instead of it stopping at a certain amount of revs it just revs too much.

https://www.youtube.com/watch?v=ZsaQY6CYS0I

 

[c5vettster]

This type of up-and-down change in rpm is typically observed when an engine is starved for fuel e.g. fuel-air mixture is too lean. A dirty calibrator is the likely culprit.