Just had a couple of hours of playtime at hand, so i mounted a pulley on the engine, grabbed a handful of goodies from the "genny-bucket", and set up a simple "powertest".
The engine is pretty capable of running a load, but the mixture needs some attention, since fuel issues killed it on every single run, when having this load on.
No problems with that at all when it just idles.
And by the way...
Might well be that they run pretty cool when idling, but after burning a full tank of gas under this load, the water actually gets hot enough to throw a bit of steam of the surface.