Expanded charging system guide (In progress)

[QWERTYMage]

I checked the Reg/Rec (Mike's XS #24-2089) using the Limey Bikes walk thru and got no voltage:

"To test this it’s very simple… just connect the BROWN wire to a live 12V feed and the Black to ground, the measure the voltage at the GREEN wire and it should read close to 12V. If it doesn’t, the unit is bad."

Could this be the cause of the failed slap test as well?
If I jump battery to the positive brush, would that make a slap test work?

Thanks for the help.

 

[TwoManyXS1Bs]

...If I jump battery to the positive brush, would that make a slap test work?

Yours is a '75? Then, yes, if the rotor is in good shape.
I'd disconnect the reg wiring to that positive brush first, though. If the reg is *really* bad, it may short your jump...

 

[QWERTYMage]

1975 XS50b: I got a new reg/rec from Oregon Motorcycle Parts. Still not charging. Won't pass the slap test. I just tested the brushes (positive to the battery tender, negative to each brush, and I'm getting battery voltage on the both brushes - my positive brush is grounded... would this hint to the rotor being grounded?

 

[peanut]

1975 XS50b: I got a new reg/rec from Oregon Motorcycle Parts. Still not charging. Won't pass the slap test. I just tested the brushes (positive to the battery tender, negative to each brush, and I'm getting battery voltage on the both brushes - my positive brush is grounded... would this hint to the rotor being grounded?

follow the power.

on the 75 model the inner Rotor brush (ground) goes straight to permanent ground on the chassis (black wire) Only on the later models is the rotor grounded via the regulator.
The regulator and rectifier should be seperate on a standard 75 model

1. Put the black lead (negative ) of your multimeter on bare metal anywhere on the frame .
Then turn ignition on and test that you have 12v+ at the outer brush of your rotor with the red positive meter lead .
( turn the ignition off for the following continuity test ) added for clarity
2. Then turn your multimeter to 'continuity' and with the black lead still on the chassis test with the red lead on the inner rotor ring that you have continuity .

The inner brush of your rotor should go straight to ground via the stator connector (black wire)

 

[gggGary]

Remember all this stuff is easy to swap, a PO may have changed to a later type system or some homogulation of parts from various machines that may have never worked together. As Yamaha delivered 70-79's the inner brush is grounded to the stator frame with the brush mounting screws as well as through the wire peanut mentions.

 

[QWERTYMage]

Sorry for any confusion, let me try to explain it another way...

My Multimeter positive is on battery positive. My multimeter negative is on the positive brush. I am reading Battery voltage. Which is telling me the brush (and the rotor it is touching) is grounded. If the positive brush wasn't grounded, it would give me a reading of zero. No?

 

[retiredgentleman]

Put your VOM negative lead on the battery negative terminal (ground). Then put your positive VOM lead on the left outer brush. Turn the key on, and you should measure about 10.3 to 10.5 volts.
Have you measured the resistance from one slip ring to the other slip ring? Have you measured resistance from either slip ring to the rotor frame (ground)?

 

[5twins]

Since one slip ring is connected to the other slip ring through the rotor windings, and the other slip ring is grounded by the inner brush, what you're seeing is probably normal. I don't think what you're doing is a valid test for anything. Just do the regular rotor test as RG described .....

For the brush wires, the only thing you do is test them to make sure they're not broken .....

 

[peanut]

@ RG
If the PO tests the power supply and ground the way that you suggest from the battery it won't tell him if the rotor or the engine itself is grounded will it ? if the rotor isn't grounded to the stator (engine) or the frame then your test is not going to reveal that

QUOTE
Put the black lead (negative ) of your multimeter on bare metal anywhere on the frame .
Then turn ignition on and test that you have 12v+ at the outer brush of your rotor with the red positive meter lead .

I had already explained clearly that the rotor inner brush is permanently grounded on the 75 model.

 

[650Skull]

Can't have power on when doing a continuity test.............. Set the meter to volts to test for live power voltage..............Continuity to Om setting

 

[peanut]

Can't have power on when doing a continuity test.........

I wasn't suggesting that he did although perhaps as the po cannot follow a simple electrical test instruction perhaps I should have said to make sure the ignition is turned off and peanut butter may contain nuts

 

[retiredgentleman]

Sorry for any confusion, let me try to explain it another way...

My Multimeter positive is on battery positive. My multimeter negative is on the positive brush. I am reading Battery voltage. Which is telling me the brush (and the rotor it is touching) is grounded. If the positive brush wasn't grounded, it would give me a reading of zero. No?

If the positive brush (left, outer brush) is grounded, then the main 20 amp fuse should blow immediately, as that would be a short circuit. Did the fuse blow?

 

[retiredgentleman]

@ RG
If the PO tests the power supply and ground the way that you suggest from the battery it won't tell him if the rotor or the engine itself is grounded will it ? if the rotor isn't grounded to the stator (engine) or the frame then your test is not going to reveal that

QUOTE
Put the black lead (negative ) of your multimeter on bare metal anywhere on the frame .
Then turn ignition on and test that you have 12v+ at the outer brush of your rotor with the red positive meter lead .

I had already explained clearly that the rotor inner brush is permanently grounded on the 75 model.

My testing method is not a test of the rotor body or engine grounding. My testing in post #327, is to determine if the correct + voltage is present at the left outer brush. I can't help QUERTYMage anymore until he replies with the result of my testing.

 

[650Skull]

I wasn't suggesting that he did although perhaps as the po cannot follow a simple electrical test instruction perhaps I should have said to make sure the ignition is turned off and peanut butter may contain nuts

Before you edited your post, it read as leaving the power on when changing from testing voltage to continuity.....................For a novice............as the Op must be or he would not be asking these questions........your post contained information likely to cause damage or harm..............making fun of the OP in light of me pointing out a correction to this fault is in poor taste....................

Mined you i am easily confused because i thought peanut butter contained Butter............ and Peanut was used just to scare off people who did not like peanuts

 

[peanut]

Before you edited your post, it read as leaving the power on when changing from testing voltage to continuity....................

point taken and that is why I amended my post.

 

[peanut]

My testing method is not a test of the rotor body or engine grounding. My testing in post #327, is to determine if the correct + voltage is present at the left outer brush. I can't help QUERTYMage anymore until he replies with the result of my testing.

yes I appreciate that ......but to be fair all you did was replicate what I had already proposed without giving me credit .
The reason I suggested testing the positive outer brush by my method was because it performs 3x tests simultaneously !.

Test 1. that there is 12v+ on the outer brush .
test 2 that the rotor windings are not open circuit
test 3 that there is a ground connection from the battery to the frame .

 

[peanut]

Sorry for any confusion, let me try to explain it another way...

My Multimeter positive is on battery positive. My multimeter negative is on the positive brush. I am reading Battery voltage. Which is telling me the brush (and the rotor it is touching) is grounded. If the positive brush wasn't grounded, it would give me a reading of zero. No?

sorry in the ensuing bun fight nobody addressed this question.
the answer is no! all you are doing is connecting your multimeter to 2x seperate 12v+ supplies which will give you no reading on the meter

If you watch my video right through it will explain exactly how the charging system works however a quick explanation might help.

The stator outer brush is fed by a 12v supply when the ignition switch is turned on.
The outer stator brush feeds that 12v into the outer Rotor ring via the brush.
Once in the rotor the 12v feeds round the wire coil in the rotor until it reaches the inner rotor ring.
It is then fed out of the inner rotor ring, via the brush,into the inner stator brush holder.
The inner stator brush holder then connects directly to ground -0v on your 75 model with a black wire to the regulator and a seperate black wire to a tag on the stator body as described by gggary that basically completes the circuit.

This electrical circuit through the rotor creates a magnetic field in the rotor which when spun inside the Stator generates a AC voltage in the stator windings .
This Ac voltage is then rectified by the rectifier and regulated by the regulator . Thats a very basic description to give you an insight into how the alternator charging system works.


You need to do the 2x tests I suggested in my original post but in addition because we do not know what the previous owner (PO) has done I would suggest that you disconnect the electrical connector on the regulator and rectifier to do the tests.

If the wrong regulator rectifier has been fitted or something incorrectly wired you may need to check the fuse hasn't blown

 

[QWERTYMage]

Hey, gang. Sorry. Certainly I AM a novice (severely mathematically challenged to boot), and realize I am not doing this right. I was trying to get my head around all this and was testing the outer brush to see if it was indeed supposed to be grounded or not.

All this is super appreciated (your time is valuable, as is your knowledge). The connector blocks are located in a place that makes it difficult to reach with the multimeter I have without a second pair of hands to help reach them... and I'm all by myself with this project. Trying to find another way to measure the voltage that is physically accessible too.

I will need to read the posts above a few times to make sure I'm reading them correctly.

As far as the rings go, I did measure them (the rings directly, still mounted to the bike) and am getting 5 ohms between them. The fuse is not blown.

I'll circle back tonight after I read this thread a gain and try to get some decent ansers before I ask any more questions.

(And I can appreciate a bit of ball-busting - since asking dumb questions warrants it. It's all good, gents.)

 

[650Skull]

(And I can appreciate a bit of ball-busting - since asking dumb questions warrants it. It's all good, gents.)

I'll bust your balls about this............................There are no dumb questions, it would be dumb not to ask...........................

 

[QWERTYMage]

Put your VOM negative lead on the battery negative terminal (ground). Then put your positive VOM lead on the left outer brush. Turn the key on, and you should measure about 10.3 to 10.5 volts.
Have you measured the resistance from one slip ring to the other slip ring? Have you measured resistance from either slip ring to the rotor frame (ground)?

Finally found a few minutes:

about 5.5 oHms ring to ring
infinite resistance "0F" ohm Outer Ring to frame

Continuity ring to ring: yes (it's a closed circuit)
Voltage at the positive brush with the key on: 0

Still not passing slap test