DT125R FORUM

I've got an update. It's been a while since I've got a new stator but there is some inconcistencies in the service manual. Before I mentioned that the resistances reading match the manual. But that's regarding the values mentioned in the troubleshooting section. I'm referring to page 8-11 in the ignition section point 7. source coil resistance. There they mention 192-288 ohms which was where my old coil was within. That's over both source coils if I'm not mistaken. However the new coil has different resistances. And those actually match the values in the manual on page 2-8 general specifications - CDI source coil. There they specify both resistances: 730 and 600 ohms +-20%. So it seems there is an issue in the manual but also my old stator matches the troubleshooting value and the new one the ones in the general specifications... Regarding the old measurements. It turned out that the voltage in the traces above are the same for the two coils in series as well as for the small one alone. The big one actually outputs 0V so there is definitely a short under load in the bigger coil. Regarding the new coil. I measured both independent and I got a sine wave with 90Vpp (peak peak) for the smmall and for the bigger one around 460Vpp. So way more than before. If anyone is interested in the scope traces I can upload them as well. So I decided to just give it a try and it worked just fine and I've got spark again!! Buuuuuut.. the first test run, after roughly 50km I lost the spark again. Turned out that the stator got that hot that the solder liqifyed and all the cables detached from the source coil.. Also the stator tooth touched the flight wheel at some point since I saw some scratches. So I thought that's the cause why it overheated. So adjusted everything a bit and resoldered the cables and it worked for some time now without scratching and overheating. Until yesterday.. after some time going up hill the bike just turned off again and barely started again. I just made it home. Today I've checked it again and one cable was again detached from the coil. Now I'm thinking if the overheating was the root cause all the time which might also destroyed the old coil. But this leads me to the question what could cause this overheating. Could it be that the engine generally runs too hot? Does anyone have a clue what it could be?

The mot guy put an advisory on my bike about the lights at tickover. Reckoned that the stator was buggered. I tried to explain to him but ‘he had one when younger’ and so was right

@ksk-04 That sounds like the right one... Check where the wires come out above the gear change lever. The magnetic pickup wires can become bare where they pass through the rubber... You should have a good strong bright continues spark when you give it a good kick over. Not just one or two weak sparks. Try getting an irridium plug for a stronger spark...

Put the Yamaha part number into Google / Ebay and try looking at various different countries around Europe (do this in settings).

@Calum Yeah checked the fuse at the battery. Don’t know if there are any others?

@Mike1992 well the issue was that one wire had broken and after one evening of riding and doing some wheelies my stator blew and now im looking for a new one