Collectordudimus

Thanks so much for the information on this. This will help me to better understand the electrical system. I will post the results to everyone who has replied. I also had one other reply which was another approach so, I will have a couple of options to try. Regards Chris

Thanks so much for the information on this I will try this. I recognize the positions and wires discussed, from my wiring diagram. Regards Chris [quote name='Cynic' date='11 April 2010 - 02:57 AM' timestamp='1270976253' post='117223'] Right, this is lifted from my manual. When i mention the colours and the terminals, the text seems to assume you have it in bits. I would take it you can do these checks from the regulator position. First you have to disconnect the A(white) and F(green) wires The white is from the Armature circuit and the green is from the Field circuit. Ground the F (Green)to the E (black) with a jumper wire. Now connect the positive terminal of your multimeter (expect around 14v) to terminal A(white) and ground the black wire from the meter to the engine. UNDER NO CIRCUMSTANCES RUN THE ENGINE OVER 2000RPM OR YOU MAY DAMAGE THE SYSTEM. The irony of the next statement is not lost on me but i didn't write it. Run the engine at 2000rpm?? and you 'should' get 14v. Reassembly is the reverse yah yah yah. As i said at the top i havent done this myself but that is the instructions from my manual. A good battery is also a given but you say it starts so i take it thats ok. Hope this is a help....

Hi all, I have a 1976 Yamaha 125. When I purchased it the generator/starter didnt work but I could kick start it easily. I took it riding and the battery drained and it died (no charge). I have been working on this part of the bike. The starter part of the assembly now works fine, but I don't know how to tell if the generator assembly is charging. The test I usually perform on the other bikes is to take the positive terminal off the battery and see if the bike dies or keeps running. In the case of the 125 the bike dies. this bike does not seem to have a magneto, but has an inner armature couplewith a stationary assembly with all the wire hookup on it. I purchased some used assembles and now have good brushes and wire connections. I have not changed the inner armature out yet, but everythingt else. the voltage across the battery is aprox 12.5V. How do I determine if the battery is being charged. The lights don't brighten up when revving to higher RPMs. If the battery is not being charged then is the armature the problem?. Looks like I may have to get a special puller for taking it off. Anyway let me know if you can help? Thanks Chris