Am I ever glad I bit the bullet and paid almost twice as much for a KATO generator for the Kubota. With the H9000 Delco regulator, and Woodward governor. No load to full load Hz 59.9 Hz to 60.0 Hz. 119.70 vac to 120.66 vac
A person has to be careful with alternating current and digital sampling rate of meters. RoyB's excellent illustrations visually portray things that no voltmeter can ever show. A meter may say "Ooooooo 120 volts!" A motor may not agree - to the point of catching fire.
Whenever a frisbee grade generator is connected to an electric motor CHECK MOTOR TEMPERATURE WITH YOUR HAND before assuming it's a great marriage. Resistance heating loads the generator, but an electric motor checks the waveform in a brutal primitive way. I have a Marathon 5 HP liquid transfer pump and the KATO waveform on the scope ends up looking better than CFE power during motor startup.
A rational way to guesstimate the quality of a generator head is weight. Actually the quantity of copper in the windings. A smaller generator with lots of wire but similar potential will almost always offer better waveform and loading characteristics, than an el cheapo.
Remember, an ISOLATION TRANSFORMER will clean up a wave form a lot.
Some of the garbage I have run into looks like a dental chart from a Great White...