Serpentine drive off flywheel?

[WGB]

Today I used an EUI meter, it was worse than the Kill-a-Watt.
The same load on utility power both meters are rock solid.
Resistance load on the generator is steady.
Any ideas?
Or is this normal?
Thanks

[WGB]

It is possible that the wave form your generator is creating is right on the edge of a double trigger of your hz meter due to a misshapen or spikey output.

With a head thats supposed to be less than 5% total harmonics?
Thanks