The Hondas don't - They actually convert to DC and then put it through an inverter. Interesting stuff! When I was in school about ~12 years ago someone said they couldn't get a perfect sine wave via that method... But they were wrong. I did it in lab last semester (low voltage), and that was the first application I thought of was a generator. It'd go something like generator -> rectifier -> DC converter -> square-wave oscillator -> high-order low pass filter -> amplifier. Completely independent of engine RPM, which would simply need to be high enough to create the necessary output from the generator (or do they use alternators on these things? I don't know.) Cool stuff.
Careful. There are "inverter" Hondas and Hondas that are cheaper and no better than the cheap junk at Harbor Freight.
You see a lot of the older Honda four-strokes on Craigslist cheap, and there's a reason if you look up their specs.
And they *all* put out nasty stuff when the engine surges as they run out of gas, no matter how clean their output in a normal running state, of course.
A whole lot of "household" UPS devices put out some silly looking not-exactly-sine-waves too. And many don't even cut their batteries/inverters in until they see "something bad" on the input.
The load gets a full whack of badness until they go click (relay tripping) and start beeping.
Continuous inverter or "in line" UPSs are three times the price of things like the "APC" brand consumer-grade stuff.
Honda is also said to be in desperately short supply of higher output gensets with the Japan situation, and probably will be for some time. Depends on where they actually manufacture the units, but they're out of 'em in Japan.
A friend recently recommended Honeywell as a good alternative. There are also a lot of cheap Chinese-made Honda knock-offs these days. Many of them aren't worth the dollars spent on them. Some are.
Pays to do research on those. RVers forums online are full of often-uneducated comments on them, and if you can read things like "damaged my heater motor" as code for, "sucky dirty output", you can learn a lot trolling the Net for deals.
A technique is to use a genset only as a charging device for a large battery or bank of batteries that are really carrying the load. It looks "Hillbilly" but can often produce perfect results when measured with a n O-scope that a cheap 4-cycle genset alone, can't touch.
"Clean" power isn't cheap. "Dirty" power is cheap and can be cleaned up pretty easily but most folks just run the dirty power into expensive devices and hope they survive.
If you have a cheap 4-cycle genset, get a voltmeter and put it in one socket of a power strip connected to the generator and then plug in a hairdryer and flip it on -- you'll hear and see the results. (Note most hair dryers are going to suck down a whole lot of watts and they do it continuously. Don't do this without a genset rated for the maximum load. Turn the hair dryer on and off.)
Many wise old residential electricians use hair dryers as load testers. They're compact, cause massive load almost instantly, and can be shut off just as fast, to see how bad the genset hunts. They're also easily carried from room to room due to size/weight.
I have four C & D Technologies UPS12-310FR batteries I keep topped off in the basement for electronics with a Battery Tender brand "smart" charger.
I'll feed the dirty stuff to the furnace controller and blower, and the fridge. Whether they'll survive it or not, is questionable. When the budget allows, I'll get them a nice inverter-style genset.
Would prefer to just pour a concerete pad and add a natural gas genset and automatic (or manual if budget was tight) transfer switch to the house's load center, but that's way out of the budget right now.
One other thing to watch in generator specs... Many are not rated to run 24/7. And some have an hour-number-based "TBO". Run-out gorgeous Hondas are also on Craigslist and eBay all the time.
Just like airplanes.
