Electrical craziness

[Alaskaindy]

Hi everyone, new to the forum. Full time bike mechanic from Indianapolis. I've ran into something I've never seen before and I know these bikes have electric gremlins. When I go to do the standard first step charging system test by checking voltage when running it got real crazy. Just touching the negative battery terminal with the negative lead on the multi meter started making the voltage jump all over the place. From 9 volts to 19 and everything in between. Jumping around so fast you can barely read it. Same thing with just the positive and with both leads on both posts. I've been working on bikes for years and never seen this. Hoping someone on here has with these xs's. It's a 79 xs 650. Really nice bike, 2300 original miles. Thanks in advance for any help.

 

[TwoManyXS1Bs]

Welcome to the forum, Alaskaindy.

The original '70-'79 charging systems use a mechanical relay-type regulator, which *could* be injecting enuff noise in the system to upset a multimeter that's not equipped to handle wierd voltage swings.

Could try a different meter,
or temporarily unplug the reg.

If it settles down with the reg unplugged, suspect the charging system.
If it still jitters with the reg unplugged, suspect everything else.
Not terribly unusual if the bike still has 40-year-old connections, what with the vibrations and age...

 

[retiredgentleman]

The most likely cause is the old stock regulator. Does the VOM measure the battery voltage normally, when the engine is off?
For a 1979, a VR-115 automotive regulator will work very well.

 

[mrtwowheel]

Supernatural indeed. Keep us posted, very interesting. Try a different meter?

Scott

 

[peanut]

sounds like the regulator is packing up but it could also be a poor connection anywhere in the charging system like worn brushes, dirty Rotor tracks etc.

On the 79 the regulator regulates the charging system by connecting and disconnecting the 12v+ supply to the Rotor (green wire) according to battery voltage and load. The regulator is fed in turn by the 12v+ brown wire from the fuse block
Check and clean the brown wire connection both at the fuse block and again at the regulator connector . Check the green wire from regulator to outer brush on the rotor .
On the 79 the inner rotor track is constantly grounded both at the brush holder (via the stator body ) and by the black stator wire which connects within the loom to every other ground wire and the frame .Run a temporary bypass wire from the inner brush directly to the battery negative to make sure you have a good ground from the rotor.

You could check the AC output from the Stator is stable . With the engine running and the rectifier connected you should measure around 10.5 to 11 volts AC at the rectifier connector I believe but it would probably be easier at that point to substitute a good regulator to test that and a good rectifier also. There should be a testing guide for rectifiers somewhere in the tech section

 

[650Skull]

Have you checked the vin no.............sometimes the manufacturing date is mistaken for the year of the bike......Does the bike run points ignition or Factory electronic ignition, (TCI).

 

[Bob Kelly III]

Sounds like the Meter to me.... I had an old analog meter that when I set it to dc it sometimes wanted to see AC instead...
( the switch was going away) sounds like it's reading both AC and DC at the same time .... I would try another meter even if I had to borrow it from someone. just to prove the meter is working correctly or not.
My current Digital VTOM i have had to repair the switch 2 times already but it was made so flimsy inside there is nothing I can do to fix it .
it's a shame too because it'a a good meter but the way it is I have to make extra sure it is in the right position and reading what I think it is !
.....edit: Ummm if the meter is registering something with only one lead hooked up and the other not.... that means it is picking up electrical radiation RFI... if you will.
In my Ham days My meters would all dance when I was talking on 40 meters LOL
so.... sounds like brushes hopping around......something ain't right somewhere to give off that kind of RFI
with the bike idling turn on a radio and tune to no station.... then see if you can hear the motor running ....<GRIN>

Bob........

 

[gggGary]

Yes digital meters can act pretty funny somedays. Positive you had it on the correct scale? Battery load tested, fuse replaced? For basic testing a light bulb (12 volt load) will tell you more than a meter.

 

[gggGary]

PS welcome aboard Alaskaindy!

 

[Monster Rat]

Welcome Alaskaindy. You have come to the right place. These guys know their stuff. I was having similar issues and it turned out to be my voltage regulator and a bad ground to the rectifier. Just follow the troubleshooting tree and you WILL find the problem.

 

[5twins]

Yes, do check the continuity of the 2 brush wires. The harness from the alternator runs through the left cover and under the chain. If routed correctly, it is well protected, but if someone changed it, the chain can chew it up.

You shouldn't have to worry about the grounding for the inner brush. It's 3 mounting screws take care of that. What you might have to worry about is the black wire running to it. I don't think that wire connects to the other grounds in the harness. It just runs directly to the regulator. It's not sending a ground to the brush, it's picking one up from it and sending it to the regulator.

 

[peanut]

You shouldn't have to worry about the grounding for the inner brush. It's 3 mounting screws take care of that. What you might have to worry about is the black wire running to it. I don't think that wire connects to the other grounds in the harness. It just runs directly to the regulator. It's not sending a ground to the brush, it's picking one up from it and sending it to the regulator.

i'd have to question that 5T

....one should never assume anything when testing for an electrical fault .

Without being able to see the bike we cannot know for sure that some idiot hasn't tried to insulate the brush holder or fit one for a later reg/rect.or that the stator and engine arn't grounded

The Regulator doesn't pick up a ground from the stator brush assembly it can get one direct from the frame fixing point if it needed to .The stator brush holder could never be relied upon to provide a sound grounding for the regulator and rectifier as it relies on the contact between the brush holder and stator and the stator and crankcase and the crankcase to the frame
Both the regulator and the seperate rectifier on 79 models get their grounds from various points on the bike frame , via a network of black ground wires .
Thats how I see it from studying the schematic and looking at my 79 2F special but I'm open to being proven wrong on this
.

 

[TwoManyXS1Bs]

...You shouldn't have to worry about the grounding for the inner brush. It's 3 mounting screws take care of that. What you might have to worry about is the black wire running to it. I don't think that wire connects to the other grounds in the harness. It just runs directly to the regulator. It's not sending a ground to the brush, it's picking one up from it and sending it to the regulator.

...The Regulator doesn't pick up a ground from the stator brush assembly it can get one direct from the frame fixing point if it needed to .The stator brush holder could never be relied upon to provide a sound grounding for the regulator and rectifier as it relies on the contact between the brush holder and stator and the stator and crankcase and the crankcase to the frame
Both the regulator and the seperate rectifier on 79 models get their grounds from various points on the bike frame , via a network of black ground wires ...

Yup, this is an incomplete research project. Some time ago, I unraveled my other '71 XS1B's harness, and discovered that both the green and black wires from the regulator ran singularly to only the brushes, via the alternator connector.

I made reference to this in these threads:

http://www.xs650.com/threads/alternator-rotor-inductive-kickback.42605/
http://www.xs650.com/threads/an-led-ignition-timing-light-experiment.44586/
http://www.xs650.com/threads/nylon-screws.43874/

For the 70-71 XS1/XS1Bs, I'm sure that the black grounding wire from the regulator goes only to the grounded inner brush, and is the only source of grounding for the regulator.

This is an unknown for the later 72-79 models, and would need confirmation.

The test is simple.
Disconnect the black wire lug from the inner brush.
Unplug the regulator connector.
Test for continuity between ground and the connector's black wire.
On my '71, I get NO continuity, confirming that this is an isolated black wire.

If any other bikes show continuity to ground, then that black wire does indeed connect to other internal ground wires. It would be great if the community could add to this trivia item...

 

[peanut]

interesting post 2M .not sure I understand exactly how you are disconnecting and what you are testing though but its gone midnight and I'm really tired . it will probably make more sense in the morning.
Have you looked at the Wiring Diagram for this model 7-5 (XS650Sf & XS650-2F) ?

The problem with electrical schematics is they are .....well basically abstract representations and can be very frustrating to use for circuit tracing.

That said ...when we refer to the Yamaha wiring schematic it is clear that whilst there is no direct ground link shown between the inner brush and ground from the stator body ,... we know from observation that the inner brush holder is not insulated from the body of the stator and therefore a ground source is apparent via the metal body of the stator and the crankcase via the stator fixing bolts .

The schematic shows a common ground source between numerous components around the bike represented by a black wire. In reality this is in all likelihood a representation of an electrical connection which may not be by a cable but through the frame of the bike, the crankcase , the handlebars and the metal housings of various components etc.

My contention is that irrespective of how the inner rotor ring gets its ground , if an independant bypass wire is connected between the inner brush and the battery negative on a 79 and there is any measureable difference in the stability of the charging output then that would indicate a grounding issue somewhere.If there is no change then that test at least eliminates grounding as being part of the issue

One of these days I'll put my new wiring loom on my bike and then I'll strip the existing loom and check everything against the various schematics .

 

[TwoManyXS1Bs]

Great, Skull. Looks like someone at the Yamaha harness department woke up and fixed this, at least on the '78 (?). So, this fix likely occurred somewhere in the 72-78 models. Any '72s and '74s out there?

 

[peanut]

so looks like I was right about the grounding afterall .
Glad to see that i can still read a schematic in my dotage

 

[peanut]

My post only shows a loom that has the separate reg and rect getting their grounds from the frame ground.............no where have i proved anyone right or wrong...................

if one make assumptions about another model/year based on a post relating to a different model/year then a rude awakening may be in store.

To quote you Peanut........."one should never assume anything when testing for an electrical fault ."............and looking at the 78SE wiring loom, (as with most of the wiring looms posted in the tech menu), i am recognizing faults more readily as i become more acquainted.

Between 1970 and 1979 there are 9 looms and another 4 others including the 79SF.............of course then there are the Oceania, European and Jjapanese models that have differences again...........what another 10-12 looms, most don't have any diagrams on the net that i know of.............nor have i seen in any of the European 650 club sites.

I made no assumptions I simply read the electrical schematic which is something you seem unable to do.

The posters bike is the same model year as mine 1979 with exactly the same wiring schematic in case you've forgotten in your haste to try and rubbish me and my posts all the time.

you really are a complete and utter t****r skull and its about time somebody did something about your continued hostility, harassement and bad mouthing other members .Occasional bits of Information from you is never worth all the crap that constantly comes with it .
I try to bite my tongue every day but sometimes ........

 

[650Skull]

im a tossing out of here

 

[Bob Kelly III]

Yep that's Skull alright...piss someone off now he's happy ! and all the administration does about it , is tell us to grow thicker skin !
but it's not a matter of thicker skin guys ! geez !
.....
Bob..........

 

[650Skull]

Yep that's Skull alright...piss someone off now he's happy ! and all the administration does about it , is tell us to grow thicker skin !
but it's not a matter of thicker skin guys ! geez !
.....
Bob..........

Ah...... the peanut gallery has arrived...........

Is this a part of your get Skull banned obsession/crusade........lol