Magneto Cut-out Not Working

snatchpiece · Post by **snatchpiece** » Mon Feb 28, 2011 4:12 pm

Ventured out to the garage to fire up the G12, it started a treat, ran it up and down the drive a few times to check everything over and all is well but.........I can't stop the darn thing, I pressed the button on the end of the mag but it wont stop, it slows down a bit but keeps on keeping on. I've had the end cover off and all seems well inside, the button is making contact with the central bolt, I don't know where else to look, electrics are not my given subject.Edited by - snatchpiece on 05 Mar 2011 3:04:29 PM

Don Madden · Post by **Don Madden** » Mon Feb 28, 2011 4:27 pm

You need a good ground for the kill switch & for the mag internals. The brass contact assembly should have a brush that rides on the end plate of the mag behind the contacts, also the one on top at the drive end. If wet with oil or worn, they won't make good contact. First attach a lead to the mag cap & touch it to the engine. If it stops, the problem is in the switch circuit, otherwise, the mag. Cheers, Don.

itma · Post by **itma** » Mon Feb 28, 2011 5:26 pm

Powder coated frame?

wilko · Post by **wilko** » Mon Feb 28, 2011 10:21 pm

On a BSA forum someone's having the same problem, but the brush behind the points wasn't mentioned. Now i can tell them how clever i am!!

Don Madden · Post by **Don Madden** » Tue Mar 01, 2011 12:00 am

The good, earlier brass contact holder had the brush. The cheap, later steel ones do not. Cheers, Don.

MikeM. · Post by **MikeM.** » Tue Mar 01, 2011 1:03 pm

If the kill button is in the end of the cap on your mag then it is possible that the reason that your engine doesn't stop when you press the button is that the earthing brush next to the mag mounting flange and situated under a 5/162 headed screw is either worn out or has got oily due to the seal in the timing case end of the mag requiring replacement. If it is the latter you can just clean the oil off and the kill button will work again, this will keep you on the road until such times when you can get around to replacing the seal. If it's just the brush then try any good mag specialist or AMC Classic spares.

snatchpiece · Post by **snatchpiece** » Thu Mar 03, 2011 2:55 pm

Thanks Don & Mike, you were spot on, I removed the earth brush from the flange end and cleaned all the crud off it and now everything works as it should. Thanks again you handsome heros.