Testing a stator

[bmwnunkie]

HI,

Posting for my Father again ( he seems to jump from one problem to another, sorry )

He is now asking the best way to test a stator ( 6v) off a C15. There are three wires, coming out, Yellow/Green, Blue and brown?

[rhyatt]

You can do resistance checks, but was it/is it charging before your dad dismantled it?

[Derek996]

I've pinched this from elsewhere that I can't remember but it should give you a guide.

Testing the Stator
As it is a coil of wire it must have two ends (Yes I know a lot of our stators have three wires) so our first test is, is there continuity through this coil? 1 to 3 ohms is the ball park figure. While at the same time this coil should not have any connection to the earth of the bike. If you don't have a multi-meter then a bulb test is very good, often a bit more instructive.
Disconnect the alternator wires from the bikes wiring. Use a headlamp bulb; you know - the one with one filament left! Fit the bulb up with a pair of wires so that you can connect it to the alternator wires. Start engine and at a modest tickover the bulb should light up enough to see that a rev up would blow it! Use the other wire if you have three, and a similar result should be obtained. Do not worry about how bright or what wires to use, just make sure that all wires are used to give an output at some time. If the bulb does light up but is less than 'brilliant' then you might have weak rotor magnets, more anon.
Finally connect one end of the lamp to the engine and the other end to any one wire, there should NOT be any bulb lighting. This would indicate a good stator. Three wires?

Since the bike isn't running the multimeter test is what you should do. Checking for continuity through each winding and making sure there is no connection to the stator itself.
I'm not aware of any Lucas alternators with green/yellow, brown and blue wires. Green/Yellow is normal but the other 2 are green/white and green/black or green/white and dark green.

[bmwnunkie]

Many thanks for your comprehensive reply.

I will pass this onto my Father.

Kind Regards