This link does not directly answer your question but provides a lot of info on that series of engine.
http://www.css-club.net/kubota_catalog/pdf/GH.pdf
For the engine to be of any real versatile use to you, check the type of engine output shaft. There are several optional shafts it could be. If it is a tapered shaft things get complicated. The tapered shaft engines were for water pumps where the impeller slid unto the taper and locked there.
Generators had armatures which used the tapered engine shaft to get connected to the engine.
If it has a tapered shaft, it is likely the end housing of the engine block will be different than a utility engine which is designed to have things like pressure washer pumps bolted to them.
Sometimes you can find a tapered adapter for the shaft and then put a pulley or sprocket on the adapter to power something.
I have a larger engine, about 260 cc, from a Honda 3500 EM Generator I wanted to make use of after the generator armature burned out which is where I got my education on tapered shaft and engine blocks. I found an engine block end from a wrecked engine so I solved that problem. I kept the armature and cut it apart to get to the armature shaft which fit the engine shaft. I am going to use it to make an adapter to go from the tapered engine shaft to a round shaft.
I want to make a pressure washer but the machine shop work I need done to make everything connect is going to be more expensive than buying a factory made pressure washer.
You could safely start your project by measuring the valve clearance of the one that is still in place and use its setting to begin with. Until you are making the engine work hard it, all it needs is a few thousands of an inch clearance. Once you have it running you can then decide how much of a gem you have. The only free on line manuals I have found want my credit card # including the 3 special numbers on the back of the cards so no go.
If it is an engine worth keeping and you still need the info, I would first ask at a dealership.
Dave M7040
