UPDATE:
Information on the generator tag is:
Kurz & Root
volts 120
amps 22
ph 1
type A
FR 608
KVA 2.5
temp rise 60*
time cont.
serial number 95266 (this one is a bit hard to read)
Further update: I took the "too soft" spring down to our local Ace Hardware and rummaged through their selection (not much). I compared all the like diameter/length springs by pulling them gently and checking it against the feel of the "too soft" spring. Not very scientific, but I finally found one that was a little stiffer. Came back home and installed it on the engine then fired it up and started plugging in heaters. The response was better, but not much. It then occurred to me that I had assumed the heaters were 1500 and 1000 watts. One tag did say 1500 and I found the other on the BOTTOM of the heater..........also 1500 watts! I had forgotten to verify the load before any testing and was demanding 500 watts more than the generator could produce.
Engine is running at 610 rpm (7 3/4" generator pulley) and I'm at approximately 4000 ft. altitude, so I suspect it's putting out approximately 5 h.p.
I backed off the governor, started the engine and then reset it....
Set the Hz at 61.5 and get 137 volts at that setting. No load, engine running comfortably, not hunting.
Plugged in the 1500 watt heater. Got 59.0 Hz and 125.4 volts (this is over half the generator's rated capacity). Engine working a bit.
Plugged in the second heater set @ 1000 watts. Got 56.5 and 115.5 volts (full rated capacity of generator, 22 amps on meter). Engine working harder, but not much.
So, my total voltage drop is 21.5 and the Hz drops 5 cycles per second. I did have to "average" the readings a bit as they fluctuated on the Kill a Watt...but I didn't cheat!
However, you'll notice that with a load the voltage is between 115 and 125, while the Hz is between 56.5 and 59.0.
May not be close to ideal, but it's a lot better than yesterday! Moral to the story: Make a checklist and follow it nextime........