80’s 18 hp Magnum charging?

[msta999]

I checked the voltage while it was running and it was only 12.4 volts, which is battery voltage, anyone know what it should put out? I have never had a dead battery, but I keep a battery maintainer on it when not in use

[Laird]

13.5 to 14.7 approx. The regulator-rectifier, that aluminum thing on the side of the engine tend to go bad. Make sure that the reg-rec is grounded at one of the mounting bolts. Not sure if 80s Magnum had a plastic cowling or a metal one. If metal , it should be grounded already. At least double check for ground. You should have approx, 35 or so AC voltage going into the reg-rec. Not 100 % on the number but a substacial amount of voltage.

[msafi65]

Check the center wire at the rectifier for voltage. It should have battery voltage. With the plug off the rectifier test for ac voltage on two outside wires. 30-40 VAC at half throttle is good. The magnums have problems with magnets coming loose on inside of flywheel and the AC voltage is low.

[Laird]

msafi65 you nudged my memory. The magnets do come loose. You can bond them in again. Couple of tutorials on utube. Terrilfixsall has one. They also get packed with dust and dirt and stop putting out the voltage.

[msta999]

Thanks guys! I'll check the voltages and see what I come up with, hopefully it is only the rectifier.

[msta999]

I have 42 volts ac going to the rectifier and only battery voltage on the middle terminal. I have another 18hp magnum engine and took the rectifier off it, I had to make leads, so I used 10 ga wire and installed it, now I have 14.2 volts at full rpm, so much better! Thanks everyone for helping me out with this.

[VillageIdiot]

Happen to have a spare clutch for that 18hp Magnum?

[msta999]

It has one on it, it is the key'd type not the threaded