Replacement

I have tried another CDI still no luck. No servo cycle and no spark. I have tried three different stators and same result. Because the replacement bits I .trying are second hand I have now way of knowing if they are ok. Is there a way to work through the bots one by one. For example can I connect the servo to the battery somehow to see if it works? I can turn it by hand so it's not seized. I don't understand why servo and coil not working. Please help.

@Calum I remember you having a Li-ion bonfire but the thing I’m most interested in is the old AC/DC bikes that have three coils on the stator. The ignition coil is horizontal on the top of the stator. The lighting and charging coils are at a V at the bottom of the stator. I don’t claim to understand it but the lighting & charging coils are both numbered the same in the Haynes manual and seem to be connected, unlike the ignition coil which seems to be more isolated. It would seem to have something to do with my investigation into why my headlight dims badly (when I have a FUBAR battery) when I use the brake lights, horn or indicators. I’m hoping that the short life of my battery’s is down to the Reg/Rec being of the oriental OEM variety that’s always been on the bike since I got it. Like the lighting coil being burnt out. It’s the last gremlin on the bike since I got it as a basket case back when the pandemic started. Unfortunately my multi metre chose this time to die, just when I want to check the coils…. The later DC only bikes (anything with more than 3coils) don’t apply to me, unfortunately ….

https://www.devmoto.com/devmoto-solutions-electriques/materiel-electrique/boitiers-dallumage-cdi-ou-tci/boitiers-prets-a-brancher/yamaha-dtr-125/

If the cabling is not messed up the main light runs directly from the stator, doesn't load the battery.

@mbmO8 Nice to hear bud, enjoy

if you buy a tail tidy online and fit it it will probably look good and work well but equally it can be very rewarding to sit down and design/make something that improves your bike and is unique. @HOTSHOT-III That's where I spend most of my time these days. I can't remember the last time I rode my Yamaha, but I'm working on it most weekend

The engine stops when the connection is made, ignition is earthed. I don’t understand what your problem is? If you disconnect the kill switch the bike will still run… If you disconnect the ignition key block connector the bike will run but have no lights… Just fit the button and try it…

Taking the powervalve apart is pretty easy, you’d be surprised how gummed up it can get too. Always worth checking that out

@Vcelicka Gonna have to check your wiring behind the headlight …