Charging system problem.

thespirit · Posted: June 30, 2006, 9:32 pm Post subject: Charging system problem.

Some of the things I have done is test the rectifier, and it seems good. I tested the coils on the stator and they are all within the right resistance. I tested from ring to ring on the rotor (brushes out), and there is 5 ohms resistance. The only thing that I thought was odd, was the brushes were connected together. The brush with the smaller metal clip was screwed into the top left of the holder (left side of the holder) and the one with the larger clip was on the right side with it screwed into the top left, top right, and bottom right. There was no connection to the bottom left screw. With the brushes out, there is a 36 ohm resistance between the two brush wires. I posted to a mailing list about it and they said they are not supposed to be connected together. So I took them back out and connected it so the left brush (small metal clip) is connected to the bottom left screw (shorter wire, non frame ground), and the right brush is connected like it was before. I put it all back together and tried to start it and it rolled over once and then everything quit. I checked the main fuse and it's blown. (It was not blown previously)...

I have very little experiance and am trying to get as many opinions as I can. Pictures of how the brushes are supposed to screw in would be ideal.

y way of thinking is that the brushes are now correct, but the resistance between the two brush wires indicate a short somewhere... Am I on the right track? I can't get the left side cover off till tomorrow when my brother brings his grinder. Someone welded the shifter to the shift rod...

kingwj · Posted: July 2, 2006, 9:50 am Post subject: Re: Charging system problem.

Here is my setup. Only 2 wires to the brushes attached as shown.

jimdi · 650Rider Supporter Joined: Oct 27, 2005 Posts: 512

It totally looks like your brush wiring is wrong to me.
I have an 81 - I am not sure if your year is different - but it should be
Lower left wire (as per your picture) is OK as is. It goes to the outer brush with the clip facing down.

Upper wire (longer thinner wire) should go to upper right screw AND inside brush - with clip on brush facing up.

From your photo - You have one brush shorted to ground. and the inside brush is upside down

Note that only the screw at 1 o'clock and 7 o'clock (as your looking at them are insulated from ground. The two screws that are at 11 and 5, are used to mount the brush holder only.
Good luck
Jim

kingwj · Posted: July 18, 2006, 11:26 am Post subject: Re: Charging system problem.

I only know I am getting 14.2 volts at 2500 rpm. The purpose of the brushes is to magnetize the rotor. Only one brush needs to be isolated from ground, the outer brush in the case of my bike and the ignition hot wire is connect to that brush. The inner brush goes to ground, completing the circuit and magnetizing the rotor. There is no way I can stretch the thin wire to make it to the terminal you suggest.

the bike is a 79 standard.

jimdi · 650Rider Supporter Joined: Oct 27, 2005 Posts: 512

I am confused - If you are blowing the main fuse, how are you getting 14v at 2500RPM?

Pull the two brush wires - test each one to ground with an ohm meter - The one that is common with ground needs to be connected to the screw that is strapped to ground.

The other needs to be isolated to it's own brush Alone.

The design must have changed between your year and my 81 OR somone modified something.

You may have to do some research to see if your setup is correct.

If you go to "downloads" on this site - I posted the Yamaha manuals for a reference.

grizld1 · Posted: July 21, 2006, 10:38 am Post subject: Re: Charging system problem.

Indeed. The 80 and later systems with solid-state reg/rec have two insulated brushes; neither is grounded. One brush lead goes to reg/rec and the other to switched power. The 79 has a powered brush and a grounded brush.

rwreed · Posted: July 21, 2006, 11:27 am Post subject: Re: Charging system problem.

thespirit,
What year is this bike? I have a 77 "D" model with standard ignition (points and breakers) and anything can blow the main fuse. Last year I replaced my front brake switch with a new one from Mike's XS and intermittently, pulling the brake or not, the main fuse would blow.

Who would have thunk it? Anyway, it can take some hunting and pecking to find a short sometimes.

Give us the year and whether it has points or Solid State ignition and we can probably offer some suggestions.

Luck,
Slim

rwreed · Posted: July 21, 2006, 12:28 pm Post subject: Re: Charging system problem.

jimdi,

FYI!
I checked the downloads and they are empty.

Slim

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Yamaha xs650