I need a little help from the experts.

Testing a portable generator that when running with no load reads about 63-63.5 Hz. add a load and it drops to about 62-62.5 Hz. The load I added was 450 watts in lights.
My meter shows 59.9 Hz when checking my Detroit Edison home power.
What I am concerned about will running a bit over the 60Hz cause problems for stuff like appliances/ furnaces that have "mother board" type of electronic controls.

A couple of years ago I had a portable that as I increased the load the higher the Hz went. I had shut down the power to my pole barn then powered it up with generator and as I turned on lights the Hz got as high as >80. Voltage reading didn't change as I increased the load.

I know my meter isn't the greatest but it is what I have. http://www.p3international.com/products/P4400.html

I often find generators that don't run so I get them cheap, sometimes free, get them running and sell them. Believe it or not,
I have scruples, I don't want to sell something that I BELIEVE will cause problems for anybody.

Thanks for any help anybody can provide!

Frequency is directly related to rpm of the engine. Is there a throttle screw you can adjust? lower rpm means lower frequency.

I'm not sure if running at higher Hz will mess up stuff plugged into it, but it does strain the engine of the generator more than necessary.

Nationwide, I believe the US grid specification +/-0.050hz, but I believe most equipment is designed for +/-3%, which is +/-1.8hz, so 63.5hz sounds a bit high.

I guess it depends on what you are planning on using it for. Lighting is relatively tolerant of frequency, I couldn't tell you what most electronic appliances will tolerate.

Also, if it's an inverter based generator, the output frequency isn't based on motor RPM, it's a function of the inverter design...

Just adjust the throttle down to your desired frequency. My grandfather, back in the day, used to run his generator a few Hz fast to correct all his clocks from the time the power went out until he could get the generator running. Those were analog clocks in those days.

Learned something new. I thought adjusting the throttle would change the voltage.
Got it adjusted to about 60.5 Hz, 650 watts of light draw pulled down to 60.2.

Will keep an eye on it if I need to power up somebody's house.