Princess Auto has a similar diesel, I've been aching to get my mitts on it, but can't justify the price... Too bad, a diesel kart would be killer!
I read all the fine print in that ad, and there's a comment about RPM limited to accomodate EPA regs, "sealed with a copper wire". I wonder how much faster it can spin with a few twists of that bolt!?!? There's a label about being certified for "constant speed only" and I'm also wondering if the range 3000-3600 rpm is nominal loaded working speed, possibly subject to adjustments. I can't help but think that it's very difficult for me to believe this pig IDLES at 3000 RPM. I could be wrong, but I strongly doubt it will only function within that range.
EDIT- I just watched the video that the ad links to- and that's idling WELL below 3000 RPM.