Electrical questions

kenb · Posted: June 21, 2008, 9:57 pm Post subject: Electrical questions

Hi guys,

I spent today fixing up some electrical issues on my 78 Special to get the bike prepared for the safety inspection, and I'm hoping somebody might be able to help me out with a couple of issues that have me stumped.

First, a little background information:

1) I need to have a look at the charging circuit. The battery is brand new and fully charged, and delivers 12.5+ volts across the terminals with the bike turned off. I'm only getting 13.7 volts across the battery with the engine revving at 2500 rpm however, so I suspect I may need new alternator brushes or something before I'm going to acheive the desired 14.5 volts that I should be getting.

2) I replaced the wiring harness today with another one I picked up in much better condition. This one has an intact fuse panel and is in excellent shape with no previous repairs having been performed on it anywhere.

3) All of the lights and signals are now functional, except that the turn signals don't flash, they just turn on and stay lit until I cancel them with the switch on the left handlebar. I'm suspecting that a new flasher will clear that up, but I'm also wondering if it might be related to the issues I'll describe below.

The confusion involves two of the lights in the center cluster between the speedo and the tach.

The white indicator light at the bottom lights up when the headlight is turned on "sometimes", but not all the time as I suspect it should be. I opened the unit up and removed some spider nesting materials from inside the cluster, and all of the wiring and socket assemblies appear to be intact. When I had the front cover off, I did notice that the bulb filament was glowing very dimly at the time, and a volt meter test detected only 11.3 volts from the center pin of the socket.

The other light that is a concern is the red light in the center. This light seems to come on and turn off randomly when ever the key is turned on, but it does show a pattern of turning off when the engine is running and revved up over 2000 rpm. When the engine isn't running, it will often turn on or off when another action occurs, such as turning the lights on or off or activating a turn signal.

The upper yellow light seems to be behaving properly, coming on regularly when the turn signal flashers are activated. All 3 of the bulbs have been tested outside of their sockets and function normally when 12 volts are applied.

So there you go guys, anybody know what's going on here? I suspect that the low charging rate may be involved, but I thought I'd check to see if any other issues may be be at work in this scenario.

Ken

dpmphoto · Posted: June 22, 2008, 12:55 am Post subject: Re: Electrical questions

are your signals stock or after market, if there after market you might need greater resistance to make them blink.Also sounds like you might need a new rotor/or stator or both.

Retiredgentleman · Posted: June 22, 2008, 12:56 am Post subject: Re: Electrical questions

Yes, check the brushes............min length is 7 mm. Good idea to clean any oxidation from the slip rings with fine emery paper With brushes removed,measure resistance across the rotor slip rings...............should be around 5.25 ohms. You seem to be getting some charging so if the ohm reading is low it would mean the rotor has some internal shorts between windings and would need to be replaced with a new or rewound rotor.
If the rotor resistance is normal, could check for voltage at the brushes to see if the voltage regulator is putting out correct voltage. On my 78SE I measure 9.5 to 10 volts DC across brushes with engine idling. When engine reved to 2500 RPM, voltage should decrease back to approx. 6 or 7 volts................this shows that the voltage regulator is working.
The white "headlight failure" could mean that your headlight low beam is starting to fail, defective headlight wiring socket, or might also mean the dimmer switch is dirty/high resistance.

kenb · Posted: June 22, 2008, 3:44 am Post subject: Re: Electrical questions

dpmphoto wrote:

are your signals stock or after market, if there after market you might need greater resistance to make them blink.Also sounds like you might need a new rotor/or stator or both.

The signals are stock. I'll be doing some investigating on the alternator tomorrow.

Retiredgentleman wrote:

The white "headlight failure" could mean that your headlight low beam is starting to fail, defective headlight wiring socket, or might also mean the dimmer switch is dirty/high resistance.

Duh, it hadn't occured to me that it was a failure warning light! I guess I'm kind of happy now that it doesn't come on all the time. I'll have another look at the connections on Sunday, as well as take another look at the service manual PDF's to bone up on some more important details like that.
Thanks also for the numbers to check at the alternator, I'll go in there for a look tomorrow to see what's up.

I've done a bit of reading up on the red light as well, which apparently is the brake/tail-light warning lamp. I guess I'll make a point of standing behind the bike to see if the taillights are acting up when it comes on tomorrow, because I've never actually looked at both of them at the same time yet.

Ken

kingwj · Posted: June 22, 2008, 8:17 am Post subject: Re: Electrical questions

The red light should come on with the application of the brakes. It is only a brake light indicator. If it is flashing without applying the brakes there is a short somewhere. The turn signal issue could be a result of bulb resistance. I got the MikesXS signals and when I installed them they wouldn't flash. They would light solid. I changed the bulbs to the old ones and they flashed. The same goes for the white light. I put in a LED tail light bulb and the white light would come on and off randomly. I guess what I'm saying is try to get the factory proper wattage bulbs in your bike, it matters.

Cooltouch · Posted: June 22, 2008, 12:13 pm Post subject: Re: Electrical questions

On my '81 Special, sometimes if the battery is a bit low from the bike sitting for a while, and I'm just starting out, I have to rev the motor to get the turn signal to blink. Have you tried this?

I don't think 13.7 volts is anything to be concerned about. That's about what my bike, with a freshly rebuilt rotor, puts out. It's plenty enough to charge the battery with the headlight on all the time, and that's all I care about.

Best,

ichael

kenb · Posted: June 22, 2008, 12:50 pm Post subject: Re: Electrical questions

Hi guys, thanks for the advice.

I've pulled off the left case cover over the alternator, and I can see that I definitely need new brushes as they are unevenly worn and they are getting pretty short. I'd like to pull the stator coil off to have a look inside, but since I don't have a manual yet (I'm picking one up this week), I want to tread carefully here.

I'm just about to remove the two phillips screws holding the assembly to the case (see picture), but I thought it would be prudent to ask if there are any surprises waiting in there for me before I do so. I'd like to get in there to clean up the contact rings for the brushes.

Ken

kenb · Posted: June 22, 2008, 12:57 pm Post subject: Re: Electrical questions

Cooltouch wrote:

On my '81 Special, sometimes if the battery is a bit low from the bike sitting for a while, and I'm just starting out, I have to rev the motor to get the turn signal to blink. Have you tried this?

Hi Micheal,
That's something I haven't tried yet. Once I get the brushes changed out and the side cover back on I try that out. I checked all of the signal lights for bad connections and corrosion this morning and everything looked OK.

The bulbs are all 1156's with the following encriptions on them: 12V32CPKK
I don't know if the 32 refers to wattage or not, but I think I'll just pick up a set of signal bulbs at Yamaha when I order my alternator brushes tromorrow.

Ken

Retiredgentleman · Posted: June 22, 2008, 1:06 pm Post subject: Re: Electrical questions

No need to remove stator cover. Just hold some fine emery paper against the slip rings and rotate the engine.

kenb · Posted: June 22, 2008, 1:28 pm Post subject: Re: Electrical questions

Retiredgentleman wrote:

No need to remove stator cover. Just hold some fine emery paper against the slip rings and rotate the engine.

Sounds good to me. I just checked the field coil resistance across the contact rings, and it tested out at 5.4 ohms, which is well within spec.

I'd like to test the stator coils as well, these are the specs I have:

Stator coil resistance:
(W1-W2, W2-W3, W3-W1)
.46 ohms +/- 10% at 20°C

Do I test this at the harness connector plug behind the carbs? I'm guessing that they'll be the three white wires I see in the wiring diagram.

Ken

Retiredgentleman · Posted: June 22, 2008, 2:03 pm Post subject: Re: Electrical questions

Yes , can check resistance at the plug between carbs and battery. Lets not forget the obvious voltage adjustment.................the voltage regulator relay under left side cover has a screw adjustment. Remove the relay cover and with engine running adjust the screw at the bottom of the relay for correct voltage.
Your rotor should work fine with that resistance.
Another check is to test if the stator is puting out the correct AC voltage. Select voltmeter to AC scale. Start engine and carefully put your test probes across any 2 of the white leads in the alternator plug ( check all 3 combinations) With engine idling reads about 12.5 to 13 volts AC. Very tight location but you can insert test probes from the battery area.

kenb · Posted: June 22, 2008, 4:05 pm Post subject: Re: Electrical questions

Hello guys,

I checked out the resistance of the stator, and the numbers came back a little higher than I wanted to see. I was using a digital Fluke meter with one decimal place on the display, and all three readings danced back and forth between .5 and .6 ohms, suggesting .55 ohms is pretty close to the real reading. The spec is .46 +/- 10 percent, so it suggests that they came in at +20 percent which is a little higher than it was supposed to be.

I cleaned the ring contacts and then put it all back together and tested the voltage at the battary again at 2500 rpm, but the voltage is still sitting at 13.7. I'll replace the brushes and test it again after that to see if there is any improvement. One of them is worn down to roughly 1/4" in length, so there can't be too much spring pressure left to press it against the ring contact.

I also attempted to test the AC voltage coming out of the stator, but the bike isn't really idling very steadily at this point and the numbers were all over the place between 11 and 15 volts. I think I'll shift my attention back to setting up the carbs better first before I attempt to do any more fine tuning to the charging system.

OK, I'm off the the Fuel category to write up another post. Thanks for the help guys.

Ken

kingwj · Posted: June 22, 2008, 4:20 pm Post subject: Re: Electrical questions

Do the swap to the solid state voltage regulator. Do it now, don't take another reading until you do the swap. Less than $30 and the mechanical regulator can be put away for your concours restoration.

xs650temp.proboards29....hread=3246

Retiredgentleman · Posted: June 22, 2008, 4:45 pm Post subject: Re: Electrical questions

If you touch the Fluke meter leads together it probably reads 0.1 ohm so when you read 0.55 ohms its actually 0.45 .............your stator coils are in good shape.
When you get your carbs sorted out, I think all you need to do is adjust the screw on the bottom of the voltage regulator relay.

kenb · Posted: June 22, 2008, 5:33 pm Post subject: Re: Electrical questions

Retiredgentleman wrote:

If you touch the Fluke meter leads together it probably reads 0.1 ohm so when you read 0.55 ohms its actually 0.45 .............your stator coils are in good shape.
When you get your carbs sorted out, I think all you need to do is adjust the screw on the bottom of the voltage regulator relay.

Thanks for all the help. You've been getting back to me so fast that it's almost like you were over here in my garage this afternoon! I really appreciate your advice.

Ken

kenb · Posted: June 23, 2008, 2:22 am Post subject: Re: Electrical questions

650skull wrote:

Ken Maxwell put out a cd explaining the wiring set up for the XS650 70-83. On some years 78-80 i think there is another circuit that runs through the brake fail light circuit and if the charging system is failing then the brake tail light warning light will come on. that can also be why the light comes on at, ignition on, then going off as the revs increase (alternator charging ) Check this out before you go chasing a short that may be non existant
The indicators not blinking but come on are an indication the bike isn't getting enough current through the circuit. you say the red light also comes on when turning on the indicators which looks to me you are on the edge to getting just enough charge and not getting enough to run all lights indicators ect

Thanks for the heads up, I think you may be right on the money here. I tried the signals again tonight while revving the engine up a bit, and I did manage to coax the signals to flash for me a couple of times. I'll be ordering the new brushes Monday, so hopefully that's all it takes to resolve these issues. It sure would be nice to know that there isn't a short anywhere.

Ken

kenb · Posted: June 25, 2008, 8:44 pm Post subject: Re: Electrical questions

Hi guys,

I got the bike idling nice and smoothly now, so I changed out the alternator brushes and checked the voltage across the battary again. It's now showing 11.8 volts at idle, and the best I can get out of it is 13.4 at 2500 rpm. It's almost there it seems, as the turn signals are at least trying to flash when the engine is revved up a bit.

Retiredgentleman wrote:

Lets not forget the obvious voltage adjustment.................the voltage regulator relay under left side cover has a screw adjustment. Remove the relay cover and with engine running adjust the screw at the bottom of the relay for correct voltage.

I tried the adjustment here to raise the voltage after changing the alternator brushes, but the screw on the bottom of the regulator has already been turned in all the way. I confirmed that backing it out reduces the voltage with my multimeter, so the regulator adjustment seems to work, but it just won't adjust any higher than 13.4 volts with the screw turned in all the way.

retiredgentleman wrote:

Another check is to test if the stator is puting out the correct AC voltage. Select voltmeter to AC scale. Start engine and carefully put your test probes across any 2 of the white leads in the alternator plug ( check all 3 combinations) With engine idling reads about 12.5 to 13 volts AC.

After I got everything I could out of the regulator adjustment I checked the AC output from the alternator, and the highest readings I got were around 11.5 to 12 volts AC.

So, I'm thinking that the regulator is toast. I'll try cleaning up some connections and test it again beforehand, but would replacing the regulator seem like the plan to you guys?

Ken

5twins · Full Member Joined: Aug 05, 2006 Posts: 1616

I don't think mine gives much more than that (volts at the battery) and it's always been fine.

Retiredgentleman · Posted: June 25, 2008, 11:31 pm Post subject: Re: Electrical questions

You can test for correct voltage applied to the rotor brushes. With engine idling use your voltmeter to measure voltage at the 2 brushes. Do you get around 9.5 to 10 volts? Rev up to 2500, does voltage decrease to 6 or 7 volts? Those are the readings I get and my regulator controls at 13.5 v for idle and 14.5 v at 2500 rpm.
Another test is disconnect the voltage regulator at the 3 terminal connector. Use a jumper wire to put full battery voltage on the positive brush (left brush). One brush (right brush I believe) is at ground potential. Start engine and measure voltage across the battery, allow battery time to recover from starting; if voltage has increased to 14 volts or more at idle and goes up to 16 or 17 when engine rev up, then that means your voltage regulator is toast and needs to be replaced.

kenb · Posted: June 27, 2008, 3:48 pm Post subject: Re: Electrical questions

Retiredgentleman wrote:

You can test for correct voltage applied to the rotor brushes. With engine idling use your voltmeter to measure voltage at the 2 brushes. Do you get around 9.5 to 10 volts? Rev up to 2500, does voltage decrease to 6 or 7 volts? Those are the readings I get and my regulator controls at 13.5 v for idle and 14.5 v at 2500 rpm.

Hello RG,
I did this test today, and at idle I get a reading of 10.2 volts. When the engine is revved up to 2500 the voltage actually _increases_ up to the neighborhood of 12.2 - 12.5 volts. It's tough to get an exact number with a digital readout when the rpms tend to wander around a bit.

retiredgentleman wrote:

Another test is disconnect the voltage regulator at the 3 terminal connector. Use a jumper wire to put full battery voltage on the positive brush (left brush). One brush (right brush I believe) is at ground potential. Start engine and measure voltage across the battery, allow battery time to recover from starting; if voltage has increased to 14 volts or more at idle and goes up to 16 or 17 when engine rev up, then that means your voltage regulator is toast and needs to be replaced.

I didn't quite have enough courage to complete this test. Before I started, I confirmed continuity to ground through the right hand brush to be sure that there was no mistake about which lead was which.

When I went to connect the jumper from the positive side of the battary to the left brush, I noticed a pretty healthy spark jumping around when I was making the connection to the positive terminal. Not the kind of "shower of sparks" you would expect when completing the circuit for a dead short, but just enough sparks to indicate that there were definitely a few amps being drawn when the circuit was connected. I ran out of guts and disconnected it at this point, preferring to see what you thought of that development before I risked hurting anything.

It seems like an interesting diagnostic test to me, as I see this excercise as being sort of a "regulator bypass" test to see what voltage is reaching the battary when the regulator is withdrawn from the circuit. Is this pretty much what we are up to here?

Ken

Retiredgentleman · Posted: June 27, 2008, 4:45 pm Post subject: Re: Electrical questions

Not sure what to think about the first test. As the alternator rotates faster it generates higher voltage and the voltage to the brushes should decrease.
Yes the second test is a regulator bypass test. The spark is normal. The rotor is designed to take full battery voltage.
As 5twins mentioned, you may be able to get by with just 13.7 volts, but I still think there is a problem and is likely the regulator.
You could try opening up the regulator and using fine emery paper, gently clean the contacts of the relay...............I have done that on mine.

kenb · Posted: June 27, 2008, 5:09 pm Post subject: Re: Electrical questions

Retiredgentleman wrote:

Yes the second test is a regulator bypass test. The spark is normal. The rotor is designed to take full battery voltage.

I'll take another shot at it then, I just wanted to be sure that I wouldn't melt anything down first! It'll be reassuring to know that the voltage is available from the alternator, and such a result would also tend to confirm a regulator problem.

retiredgentleman wrote:

As 5twins mentioned, you may be able to get by with just 13.7 volts, but I still think there is a problem and is likely the regulator.
You could try opening up the regulator and using fine emery paper, gently clean the contacts of the relay...............I have done that on mine.

I still need to coax a little more power out of the system to make the signals flash, and the fact that they do flash intermittently with the engine revved up suggests that I'm just about there.

I cleaned up the regulator contacts yesterday, but it didn't seem to improve anything. It appears that the unit is functional but it has just reached the upper limit of its adjustability. When I backed off the adjuster screw, the voltage across the battary dropped off with it, and I noticed that the external coil on the side of the regulator got very hot during the two minutes it took to take the voltage reading. Tightening the screw back up again just returned me to the same place where I started.

I'm in total agreement with you about the regulator, if I was a gambling man I think I'd have to put my money on it being toast. Thanks for all the help RG, you really are terrific.

*************

I priced out new regulators at Yamaha, and they quoted me a price for a new one at $180! Since that ain't gonna happen, I have the choice of hunting down a used stock one, or trying out one of the solid state ones mentioned previously by kingwj a few posts back.

Anybody else have any good or bad experiences with those solid state units that I should know about before I decide what to do?

Ken

Retiredgentleman · Posted: June 27, 2008, 11:58 pm Post subject: Re: Electrical questions

Yes I believe it was kingwj that said he installed the "Standard VR115" and worked perfect for him. www.rockauto.com sells it for $29.99, listed for 1971 to 1974 American Motors cars. Good price and would be very reliable.

What Happened to 650rider.com?

Yamaha xs650