Kawasaki P/N 21066-2071 Voltage Regulator/Rectifier

I am trying to help a neighbor - we trade work from time to time. He is building brush mowers using a EX-270D, 9HP Subaru engine, rope start only. He wants to delete the battery and run the electric clutch directly from the engine alternator, lighting coil. He claims the engine uses a 16 amp alternator however, the voltage regulator needs to have a battery to work properly.

I understand the P/N 21066-2071 voltage regulator is used on the Kawasaki, Series I, 17 HP engine for commerial walk behind mowers, with electric clutch, rope start and no battery. I believe this 17 HP Kawasaki engine has a 13 amp alternator however, there are Kawasaki engines with 15 amp alternators.

The simple solution would be to use the Kawasaki regulator on the Subuara engine, both are two wire outputs from the alternator. However I am concerned the Kawasaki regulator will not handle the higher output alternator. Does anyone have experience with this regulator or know if it is also used with the 15 amp Kawasaki alternators?

Also, the Kawasaki regulator uses a capacitor. The capacitor appears to be much like a motor run or start capacitor with two wires into the regulator. Does anyone know what function the capacitor serves? Has anyone used a capacitor with the Subaru regulator/rectifier to allow use without a battery?

I work on Kawasaki powered equipment. I understand somewhat what you are trying to do. I am thinking the Kawasaki stator that works with that regulator is also unique to that system. Also, usually there is a module in the clutch circuit on the mower that makes the clutch circuit work and I don't know how it works, only I do know when the module fails, nothing works.

You guys will be way ahead just putting a battery on the mower and running a regular clutch circuit.

Thanks for the reply, to expand a little: The current models use a sealed 4.5 AH battery and the Subaru voltage regulator. Yes, that makes everything simple with the Subaru engine. However, since there are no lights or electric starter the battery tends to be forgotten. At replacement time there are compliants about why is there a silly battery when there are no lights or starter.

If I under stand your situation, I would forget the electric clutch and either pivot the engine to tighten the belt or use a belt tensioner with a 3rd pulley to tighten the belt. Save a lot of money and make maintenance simpler. I don't understand why you need an electric clutch.

As you may know the out put from the engine mounted windings is A-C. The regulator has three duties, regulate voltage, regulate amperage and rectify to DC. My somewhat limited knowledge of how such things operate and how manufacturers do things in general tells me that the regulator will work with either Kawasaki alternator. As for the Subaru who knows? Just because it has two wired doesn't mean the A-C output voltage is the same. Simple evaluation sequence is to check a Subaru for A-C voltage at various RPMs, then check a Kawasaki and personally if similar I venture the $25 for the regulator and bet on it working.
We ran two Buntons with the Kaw engine, no starter or battery and electric clutch set up for many years and it was entirely reliable.