Picked up a used 2013 ZForce 600. Mechanically seems in pretty good shape. Took it to the cabin and my son used it all day driving very slowly around the gravel roads. The vehicle started to shut off and required a boost to get going again.
Voltage at the terminals while running fluctuated between 11.6V (at idle) and 12.4V (at high RPM). Given that my son was driving very slowly I surmised the battery was draining faster than the stator and rectifier could charge it.
Did some checks on the stator (magneto) and was only seeing between 6V AC and 16V AC on each of the three phases depending on the engine RPM. Made sense considering that the rectifier (regulator) was sometimes able to deliver just enough voltage to charge the battery. I checked each of the 3 phases off the stator to ground and voila! Each of the phases were grounded.
I removed the passenger side rear wheel, plastic "skid" plate, coolant lines from the water pump (which is attached to the lower right corner of magneto cover), removed the 8 to 10 bolts from the cover, the 4 bolts from the crank bearing cover and the bearing retaining / crank bolt and pulled off the cover. Unplugged the electrical stuff too ;-)
Reinstalled everything, changed the oil, flushed the coolant and VOILA! 13.8V at the battery terminals. Old stator was cooked. I hope this helps somebody else.
You'll need stator, oil, coolant and likely a magneto cover gasket.
Cheers,
Monk