[cbrrider111]

I have a 2012 CBR250RA with 90,000km (56k miles). I tried starting it going home from work today and the crank was slow, then when I got home I tried to start it again and it wouldn't turn over. I gave it a full charge and started that bike. The voltage didn't jump up when started or revved, just sat at 12.4v

I had a spare regulator/rectifier so swapped that with no success, the voltage still sat at 12.4v running.

I measured the output of the stator at the regulator plug (while connected) and got 1.4V, 2V and 3.4V AC when running, revving made little difference to the AC voltage.

I measured the stator resistance and it is 0.4ohms between all 3 windings. There is no measurable resistance from the windings to the frame/ground.

Would the stator still be faulty with resistance between the windings? Could it be something else?

Thanks in advance.

 

[DannoXYZ]

Looks like you've got charging-system issues.

Voltage readings looks like you're just measuring battery voltage. It drops lower and lower as you ride and battery discharges?

Stator coil resistance is within spec.

I measured the output of the stator at the regulator plug (while connected) and got 1.4V, 2V and 3.4V AC when running, revving made little difference to the AC voltage.

You measured this between black wires of stator plug before going into RR right? AC voltage-reading is not correct, should be 35-50vac at high-RPMs.

 

[cbrrider111]

I end up replacing the stator and there were obvious burnt windings. The bike now runs at a constant 14.2v.

 

[Mufasa]

Hey same issue I had, but mine failed at 48000km. Glad your sorted. Ride safe.

Sent from my SM-G950F using Tapatalk

 

[DannoXYZ]

good job on repair!

To prevent future overheating of stator, use series-circuit RR such SH775AA (Polaris 4012941). These only pass as much power as being consumed by electronics. Rather then running stator 100% full-time like factory shunt-circuit RR.