The generator Kubota engine does not have variable injection timing. The injection timing can be precisely set by changing the thickness of the shims under the top plate of the injection pump. The factory shimmed the injectors to run best at 1800 rpm.
The 3 arm governor has a drive gear that has a centrifugal advance mechanism to advance the injection timing as the speed increases. Almost every automotive diesel injection pump uses a built in timing advancer. It makes the engine much more responsive as the rpm and power settings change as the driver shifts through the gears.
The 3 arm governor uses the third arm to move the injector rack position more slowly than the directly connected 2 arm type. The 2 arm governor moves the fuel injector rack very quickly so extra load placed on the generator will not slow the engine down. In a car, this fast action causes the exhaust to smoke if the driver is not very careful with his foot.
In your case with a coffee grinder I think you will not have to change the shims under the injection pump. You may notice that heavy loads on the engine will cause black smoke from the exhaust until the engine once again stabilizes.
My home email address is
cbx_kim@hotmail.com if you would like to write directly. I have a spare engine and camera and can help you with your project. Cheers...Kim