Here is a Robin Subaru new engine video. A 169cc OHC rated at 5.7 hp at 4000rpm. I mounted it on my log splitter and ran it with no load for about 15 minutes before mounting the pump. I have the top speed set at 3600 rpm. I am breaking this in using a Comet axial pressure washer pump. The pump needs 6 hp to run at full pressure so this will put pretty much full load on the engine. The tiller it is going on won’t load the engine anything like the pump will, hence the break in with the pump. These Robin engines are excellent running units.
Edit………….I did run the engine/pump combo for about 45 minutes. Engine runs superb. I mounted it on the tiller and went out and buried it in the garden. Like i figured, the tiller at full depth doesn’t load the engine very much at all.