Generator mechanical question

[gomer pyle]

I have this generator(http://www.northerntool.com/images/downloads/manuals/165914.pdf). When I got it, it had been on fire, run over with a lull, buried in a trash pile, etc... there was nothing wrong with the motor or generator so I picked it up on the cheap. I have replaced the frame work, breather assembly, gas tank, and a few other small things. Some of the brackets for the carb were bent but I have it running now. I have never been around a generator before and now nothing about them.  When I first got it running,  it was idling at a nice slow speed but only putting out 60 +/- volts.  I assumed it would ramp up under load but it doesn't. I've adjusted the engine speed up until I'm getting 120v but I don't think this is the correct way to do it and I don't think it will be right under load. 

Does anyone have  knowledge on how these are supposed to work?

[peejman]

Yes, voltage (and frequency) are proportional to engine speed. Generally, a generator has to run at full speed (3600rpm) to generate full voltage. 

[gomer pyle]

But should it ramp up when it sees load or should I keep it screaming?

[Wingshooter]

The ones I've had run wide open with/without a load. Allow it to run a few mins before applying a load to give the engine time to stabilize, warm up, etc.

[peejman]

29 minutes ago, gomer pyle said:

But should it ramp up when it sees load or should I keep it screaming?

Most small generators have throttle controls to (try to) maintain constant speed, so yes it's supposed to run at full speed regardless of applied load. 

This is part of why most generators produce "dirty power". Every time the load changes, the throttle controls must react to maintain constant rpm. But they can't react instantly so the rpm varies, which then causes the voltage and frequency to fluctuate.  This is why it's a bad idea to run some electronics (computers, etc.) using a generator that produces unconditioned "dirty" power. 

Generators that are rated "electronics friendly" condition their output to minimize all those fluctuations.  They do it by converting the AC signal output to DC, passing it through a capacitor which acts as a buffer,  then converting it back to AC which cleans up the signal. 

Easiest way I know to do that on the cheap is to use a small engine (or bicycle, water wheel, etc.) to spin a car alternator and run the alternator output through a power inverter. 

[gregintenn]

Some generators idle when not under a load, then throttle up when loaded. You set the throttle on mine manually.

[nightrunner]

Has to run at full throttle to do it's job. Same as a lawn mower needs to be at full throttle or near it when the blades are engaged.