Re: 125 WITH NO SPARK
Posted: 21 Sep 2021 12:12
Hi Bill,
I sense your frustration from a far.
I do agree with others that the first suspicion has to be the generator winding.
I am not sure I have definitive data on 125H for the winding resistance (green to earth with ignition switch ON) as new,
for all others it is supposed to be 300 ohms, but in practice on the twins they work until the resistance
has fallen (due to shorted turns) until around 200 ohms.
The insulation breaks down due to heat, turns become shorted and layer to layer shorts occur which reduce the number of effective turns and so reduce the voltage being sent to the transducer.
Previously Paul mentioned how you can measure the a.c voltage (green to earth) which should increase linearly with rpm until it plateaus.
In order to remove any fault associated with the lighting coils you would have to disconnect the yellow and red wires from the stator- assuming your later 125 has the non direct lighting system.
Please don't let the rotor overheat, the magnetism could be damaged as well as further damage to insulation.
Mark
I sense your frustration from a far.
I do agree with others that the first suspicion has to be the generator winding.
I am not sure I have definitive data on 125H for the winding resistance (green to earth with ignition switch ON) as new,
for all others it is supposed to be 300 ohms, but in practice on the twins they work until the resistance
has fallen (due to shorted turns) until around 200 ohms.
The insulation breaks down due to heat, turns become shorted and layer to layer shorts occur which reduce the number of effective turns and so reduce the voltage being sent to the transducer.
Previously Paul mentioned how you can measure the a.c voltage (green to earth) which should increase linearly with rpm until it plateaus.
In order to remove any fault associated with the lighting coils you would have to disconnect the yellow and red wires from the stator- assuming your later 125 has the non direct lighting system.
Please don't let the rotor overheat, the magnetism could be damaged as well as further damage to insulation.
Mark