On Mon, 18 Sep 2017 00:51:21 +0000 (UTC), David Lesher
wrote:

I'm seeking a small engine that can drive a generator.
By small, I mean in the 12"^3 range.

It must be 4 cycle as it will need to run on propane.
It will drive a 13.8V generator, or 120VAC, say 800 watts.

If H-F Item#63025 was 4 cycle, (and it was un-junk....) that
would be ideal.

This to fit aboard a sailboat for stationary power/starter
battery recharging.

Of course, if instead you have a Diesel in that size [Ha!],
speak up.
Briggs and Stratton 800 or 900 series engines.
Northern Tool carries them. 8 ft lb torque, so 5.4HP at 3600 RPM.

$260 for the 800 series, $350 for the 900 series 6 HP (9 ft lb at
3600)
The Honda GX200 is another option - $429 at Tractor Supply.

Tose are 200-205cce engines - or 12 cu inches, which I believe was
your specification.

The GX160 is the 4HP honda 163cc. The Briggs 550 series is 127cc
4hp.