Did you ever build the trike? The 4.5 hp is GUTLESS, has fixed injection timing and was designed to run a belt driven alternator. Maybe OK for a minibike but severely lacking in power, throttle response, and fuel efficiency. All modern automotive diesels use injection timing advance. Generator Kubotas have fixed timing like a lawnmower engine.
I just got a Kubota EL 300E. I couldn't pass it up either. Mine came from a large live aboard boat and was used to keep the batteries charged when the main engines were stopped. It also came with a 3000 Watt inverter so they could run the microwave and some other 120VAC things. They went commercial and the USCG made them remove the system.
I built the Diesel Geo Metro. 24 HP is borderline dangerous here as it is not enough to keep 55 mph on the freeway hills no matter what you do. From 35 to 50mph, it was sweet running, great for flatlands, 70mpg right away. California will not allow ANY diesel conversions so it remains stored and unlicensed. It will be my Mad Max grocery getter when the meteor hits.
For electric car guys...this unit in the trunk of the car with its 150 amp alternator would allow you to recharge anywhere with no outside power. Run it when the batteries deplete. The inverter that came with my unit is also a 120VAC battery charger that will charge 12 volts at 250 amps. It came with 2/0 welding cables...huge.
If I don't hook it up to my solar/battery backup systen, then I might make it into a marital aid. Cheers....
Here it is running....