Wow, this is certainly turning out to be an interesting topic!
To my original posting, I could definitely hear the Changfa bogging down under the full load. How much exactly, I don't know, as I couldn't be in the basement flipping breakers and put the tach on the generator shaft at the same time. But, I was pegging two 2500 watt meters on the transfer switch, so I was pulling a solid 5 to 6kW from my 3.2kW generator, which is rated for 200% surge capacity. Since it's an R185, and rated 8.8hp MAX at 2200 rpm, and I'm running it at about 1870 rpm with my pulley ratio, I'm good for about 7 hp. So, I was pretty much loading it up to full smoke. I'm using a Browning industrial 6 rib "L" section Poly-V belt setup, and my drive setup is rated at about 30 horsepower, so I'm definitely not slipping.
An email to Franklin Electric came back with the reply that my well pump needs a 4800 watt generator to start. That would be a 20A at 120V unit nominal, and give 40 Amps peak. My pump pulls just over 40A at locked rotor (starting) conditions, so that works out. The big flywheel on the Changfa would have enough inertia to pull the peak load on the generator to get the pump started, but under continuous load, it would bog. Therefore, a 5kW head would provide enough peak power to start the pump, but really wouldn't give me a lot more useable KW due to horse power limitations - same issue for a 6/1 Listeroid. They are good for 3700 watts or so max continuous, but will deliver a LOT more peak power from a ST5 head due to inertia.
I've got a call into the local Markon sales rep to see if there is a two bearing 5kW head available for a decent price. I got a screaming deal on my current head from them several years ago, and a 5kW head would be plug-and-play compatible. That would give me the peak juice to start the pump, and also give me more flexibility to run 120V loads when connected 240V (peak power per winding).
I'll have to get ambitious and see if I can rig up the motor on my table saw for 240V and use it for a 'booster'. It might just supply the extra 10 or 12 amps for that split second to get the well pump going.
I just don't want to end up blowing up my setup or frying the well pump trying to screw with this. The easy solution is to just get the bigger head.
Chris