Magneto problem

[abcarswell]

Magneto stopped working in the middle of my last drive with the TT. Started by opening up the inspection cover and found this. Obviously not good but does mean I need to start a tear down?

[speedytinc]

I see a piece of copper wire & the screen magnet. I put the magnet on top of the screen in the valley. The copper wire may have been used to safety wire fly wheel bolts. (seen that before). If you built it, you would know. Magneto coils are a copper ribbon, not wire.
Any way, i would not immediatly jump to a tear down without more investigation. Do the easy stuff first.

First step is pull mag contact & clean. Then try running again. Test output voltage.

Before pulling motor, i would pull the starter & look around with a mirror.
pull dipper cover & look around.

[speedytinc]

BTW. your magnet is covering the oil hole for your brake band. Thats not optimal.

[abcarswell]

Thanks, that’s not where the magnet started out but moved. I’ll reposition and start the investigation.

[DanTreace]

Thanks, that’s not where the magnet started out but moved. I’ll reposition and start the investigation.

Might be best to wire that magnet to the screen to keep it from walking, and possibly fall into the trans.

Prior thread on that happening

http://www.mtfca.com/discus/messages/82 ... 1546707218

[abcarswell]

So pulled the starter and used mirror. Couldn’t see much but no obvious issues. Rolled engine over and nothing obvious on magnets or ring. Mag post was cleanish. Still appears no AC output although need to get test light to check properly. Could the loose wire floating around caused a ground and demagnetized mag coils? Wire is not steel but could be a safety wire.

I did not build this engine so have no history. I suspect it was done 20-30 years ago although lower hours as I have been into the head and valves and they look very tight and clean. Don’t really want to start a major project at the beginning of show season and it runs okay on battery. Am I flirting with disaster here?

[speedytinc]

Loose wire would not demagnatize. A bit of wire could ground the field coil somewhere & lessen output. Use a meter on mag post for a voltage reading. Digital meters typically wont work with the interference of t coils. Did you pull the inspection cover & look @ flywheel bolt safety wire?
Cant imagine your screen magnet "walking" It should stick where its put - magnetic!