Removing ac magneto

micklepuss · Mar 27, 2009

Hi guys, after trying to solve my problem of voltage dropping with an increase in rpm's, i've been informed that the fault is with the magnet's in the magneto which are cracked causing more poles from within and a cancelling voltage between poles.

Question is, where is the magneto? Service manual says page 7-18 that's it's number 42, i've had the cover off and nothing there, it the main crank inside isn't it? Manual doesn't say how to remove unit so any help would be great before I pull off every cover to find it.
Cheers

maleko89 · Mar 27, 2009

Hey, how did they determine bad magnets? Did they remove the cover? The magnets are part of the flywheel behind left crank cover. The stator is actually bolted to the inside of the cover. Did you use the fault finding diagram? It's in the Electrical section as a sticky. I would test the rectifier/regulator, stator and all connections in between and to the battery. If that checks out, have your battery tested.

micklepuss · Mar 27, 2009

I have been through the fault finding diagrams, brand new battery, tested R,R and voltage from magneto all ok, at low rpm i'm getting 14.2v but as rpm's increase volt drop below 13v.

I was talking to a guy who had the same problem but on a different bike and that's what he found out after checking all the same thinks I found him as he's selling of all types of magneto and was going to purchace one off him when he told me to check the magneto magnets

micklepuss · Mar 27, 2009

cheers for that info i will pull it apart and find out for sure if it's cracked, at least i now have a better idea of what i'm looking for and where it is.

naughtyG · Mar 27, 2009

Get yourself a Haynes manual - they have full descriptions on how to remove everything.

maleko89 · Mar 27, 2009

micklepuss said:
I have been through the fault finding diagrams, brand new battery, tested R,R and voltage from magneto all ok, at low rpm i'm getting 14.2v but as rpm's increase volt drop below 13v.

I was talking to a guy who had the same problem but on a different bike and that's what he found out after checking all the same thinks I found him as he's selling of all types of magneto and was going to purchace one off him when he told me to check the magneto magnets

But what are you getting for AC voltage? Check VAC between two white wires (3 tests). At 5000 rpms you should be over 50 volts.