Dick,
These instructions are assuming you have a meter, a very limited knowledge of how to use it and no troubleshooting ability.
1) First double check the Regulator wiring. Look at the Rotax regulator plug.
a) The two heavy gauge wires from the engine go the two ?G? positions.
b) The two White wires go to the ?R? and ?B? position.
c) There is NO wire in the ?L? position.
d) The small yellow wire goes to the ?C? position.
e) The plug is FULLY seated, all connections are FULLY seated.
f) The Regulator is bolted to the airframe
2) Setup the meter;
a) Connect the Black lead to the meter COM, (-) or BLACK socket.
b) Connect the Red lead to the meter V, VOLT, (+), or RED socket.
c) Do not connect any lead, to any socket marked A, AMPS, or MA.
d) Turn the meter on
e) Select DC volts.
f) If it is not auto scaling, select a range that includes 10-15 volts.
3) Connect the Black meter lead to a good ground.
4) Test the meter and ground connection by checking a known voltage with the Red lead, the battery (+) lug. This should read positive (+) 11-13 volts. If not at 11-13 volts, stop now and find out why.
5) With the Master Switch on and the engine NOT running, with the Red Meter Lead, measure the voltage at;
a) the Regulator B pin _______
b) the Regulator R pin_______
c) the Regulator C pin_______
d) the Regulator case________
6) Start the engine and run at idle speed, with the Red Meter Lead, measure the voltage at;
a) the Regulator B pin _______
b) the Regulator R pin_______
c) the Regulator C pin_______
d) the Regulator case________
After answering these questions there may be more tests. But we have to start here.