16 Volts at idle - Please help!

[glennpd]

Ok, here is the breakdown.

• Stock 80G
• New Rotor 5ohm slip ring resistance (Used)
• New wiring loom (MikesXS)
• No short on green wire
• Continuity on green
  • disconnected brush
  • connector before regulator
• Near battery voltage (-.3v) on brown wire with headlight on
• Open between green and brown at the connector
  • disconnected brush
  • connector before regulator
• Replaced the brush holder
• Brushes not grounded
• Replaced Rec/Reg (Used)
• Fully tested Rectifier (Following Ken Maxwell procedure)
• Fully tested Regulator (Following Ken Maxwell procedure)
• Not sure about reserve lighting device but who cares?
• Start motor 16v at idle ???

What else can be causing unregulated voltage?

Thanks

Glenn

 

[XSLeo]

Yes, the regulator isn't functioning. The regulator needs to read battery voltage on the brown wire.
What is the voltage on the brown wire at the brushes and at the regulator? It should be with in .2 volts of the battery. If not trace the brown wire to find the place of high resistance and fix it. Most likely the key switch.
It might be a bad or weak ground on the black wire out of the reg/rec.
Leo

 

[glennpd]

Thanks Leo,

Voltage readings:

1. Not running headlight on
   • 11.84 At battery
   • 11.53 At green wire coming out of regulator
   • 11.50 At brush holder

Since the test procedure as described by Ken utilizes the regulator ground to test regulator function it demonstrates a good ground. To be absolutely certain I tested the ground wire (black) at the regulator connector on the loom and found 6.5 ohms. I found open from the black wire from the connector on the regulator (disconnected of course).

Just seems that to generate AC the brown wire needs to excite the rotor with sufficient voltage to create a magnetic flux. If the voltage was too low at the brown wire then no AC would be generated. In this case it seems we are supplying the rotor with enough DC to create the flux necessary to create AC in the stator.

 

[glennpd]

Since I am getting no ground from the black wire at the regulator connector, that could be the problem. I tested the body of the regulator to ground and it was good, but the black wire coming from the regulator is open. Is this correct?

Thanks

Glenn

 

[retiredgentleman]

You bought a used rec/reg? Where did it come from? Maybe the PO sold it because it was defective.

The regulator must have a good ground on the black wire, and battery voltage on the brown wire, or else the reg will give full voltage to the rotor brushes and the alternator will put out >16 volts.

Its normal to have 10 to 13 volts across the brushes at idle. If the regulator is working correctly, when you rev the engine to 2500 rpm, the voltage at the brushes should go down to 5.5 to 7 volts.

 

[glennpd]

Yeeee freekin Haww

I found the problem. After studying Ken Maxwell's video again and again, a light switched on so to speak. The yellow wire could backfeed the alternator if a diode was bad in the Safety and lighting relay to the reserve lighting unit. Mmmmm. 13.5V steady.

Life is good

thanks for all your help and patience.

Glenn

 

[gggGary]

Good troubleshooting! That was a sneaky (and rare) one.

 

[glennpd]

My thanks go to Ken Maxwell in Tennesse for his comprehensive videos on the venerable 650 electrical maze. As you may know Ken sells two Cd's. The first is theory of operation and the second is component testing. you can get them and some tech help at: /ken_maxwell/http://www.mikesxs.net/ken_maxwell/

 

[retiredgentleman]

Yeeee freekin Haww

I found the problem. After studying Ken Maxwell's video again and again, a light switched on so to speak. The yellow wire could backfeed the alternator if a diode was bad in the Safety and lighting relay to the reserve lighting unit. Mmmmm. 13.5V steady.

Life is good

thanks for all your help and patience.

Glenn

Glad to hear its working. I would like to hear more about a backfeed,.........a backfeed from where? Where is the diode; is there a diode inside the Safety Relay?

 

[glennpd]

According to the flow diagrams on the video, on page 8 of 11 the yellow wire coming from the alternator into the safety and lighting relay has a diode.

 

[XSLeo]

The diode and the latching circuit are only on the later bikes where the headlight is controled by the safety relay. On the earlier bikes the safety relay just disabled the starter.
The diode and a resister is part of the latching circuit of the relay that keeps the relay tripped to keep the headlight on if the bike stalls.
On the, I think 78 and up bikes the headlight was controlled by the safety relay. They even removed the light switch on the bike.
When the bike starts the alternator output climbs from 0 volts up to 13+ volts. As it rises at about 4volts the safety relay trips. This stops the starter and keeps it from working all the time the engine is running, it also turns on the power to the headlight. If the engine stalls for any reason the latch circuit keeps the headlight lit.
To turn the headlight off to restart the bike you have to turn the key off and back on.
I never thought about how it could effect the regulator. I know that if your stator tests out to have about 20 ohms then the yellow wire needs to be unhooked to get the proper ohm reading. The coil in the safety relay has about a 20 ohm resistance.
Leo

 

[AdvSwede]

XSLeo,

So how do you trouble shoot the relay? Do you just unplug the yellow wire and check for change in battery voltage when the engine is running?

 

[XSLeo]

On the safety relay you can just unplug the yellow wire to see if it has any effect on the battery voltage.
Leo