How do I check a stator?

[Bender]

When I bought the CB125, aka The Yello Peril coz it's about the same colour as the emoticons on this site I got a Big Box Of Parts with it.

I'm having a garage stuff sell off and there's about three engines worth of spares so I plan to sell two and keep one. I just don't have the space for it all.

OK that's the background. In the BBOP are three stators - the winding bits.

How do I check if they are any good?

[CookMySock]

Check resistance between any of the output wires - should be very low but not zero - about 0.8 to 1.5 ohms ish AND they should all be identical no matter which way you measure it.

If its star-wired, check resistance from the soldered join of the three phases to each of the output wires - should be very low resistance - about 0.5 to 1.0 ohms and they should be all exactly the same.

Check resistance from the metal core to any of the wires - should be open circuit - infinite resistance.

There should be no darkening of the windings due to heating.

[Bender]

Thanks, I'll crack out the multimeter today.

[Henk]

The tests mentioned will tell you if its poper f**ked but are no garantee, you can still get insulation breakdown when the thing is running, the only way to test it properly are to either bolt it in and try it, checking the voltage from each winding or test it with a megger, not sure what readings you should expect in the later case and since there is about zero chance of you having one I'm not going to bother doing the research.

[CookMySock]

Henk is correct, and bike charging systems are notorious for having undiagnosable faults that end up having the entire charging system rebuilt or replaced.

Even a 500 volt insulation tester (commonly called a megger - I made my own) will only give you an industry-best-estimate.

If you want to sell them as "good working order - insulation tested" then take them to your friendly auto-electrician and ask if he can do a quick megger test for ya. It will genuinely take him only 60 seconds and he will give you a straight answer for probably $nix.