Odd Electrical Indicator

Bike is my 1984 R100. Out for a ride yesterday, near the end I stopped to fill up. When I went to restart the bike, the red GEN light was not lighting up with the key On. Before starting the bike I pulled in the clutch lever and when I did that the GEN light came ON. I tried that a few times and each time it came ON.

Started the bike and headed the few miles home, and when idling at a light the red GEN light was lighting up and when the RPMs rose, the light went out. At home, Same thing when I pulled into the garage, at idle the GEN light was okay, light ON. Shut the bike off and when I turned the ignition back on, the GEN light was out, not lighted. I had to check a few other items on the bike and before heading in, I tried the ignition key again and the GEN light is ON with the key ON.

I checked the battery after all this and voltage at the battery posts was 12.95 volts. Battery is less than a year old AGM Panasonic.

Any thoughts? Is this a rotor problem that is currently intermittent, but will later become an open rotor?

Recheck your battery connections and speedo ground. Couldn't hurt to be sure.

GEN Light

m_stock10506 said:

Bike is my 1984 R100. Out for a ride yesterday, near the end I stopped to fill up. When I went to restart the bike, the red GEN light was not lighting up with the key On. Before starting the bike I pulled in the clutch lever and when I did that the GEN light came ON. I tried that a few times and each time it came ON.

Started the bike and headed the few miles home, and when idling at a light the red GEN light was lighting up and when the RPMs rose, the light went out. At home, Same thing when I pulled into the garage, at idle the GEN light was okay, light ON. Shut the bike off and when I turned the ignition back on, the GEN light was out, not lighted. I had to check a few other items on the bike and before heading in, I tried the ignition key again and the GEN light is ON with the key ON.

I checked the battery after all this and voltage at the battery posts was 12.95 volts. Battery is less than a year old AGM Panasonic.

Any thoughts? Is this a rotor problem that is currently intermittent, but will later become an open rotor?

Click to expand...

It might be simple as a poor connection to the bulb in the instrument housing. If the bulb is lighting intermittently, it could be the connections either at the bulb terminals or the brushes in the alternator. It could be the rotor windings (they create the path to light the bulb through the brushes) but I wouldn't bet on it as the windings are either closed or open.

You need to probably investigate the brush connections first as it's easiest to access (front cover).

I would disconnect each brush wire terminal and measure the resistance with a good ohmmeter. That's an easy way of knowing if the connection is good from the brush to each slip ring on the rotor and back out the other brush.

RickR90s

Still nothing resolved, but a little update.

The big connector at the back of the cluster is solid. The brushes were renewed 20,000 miles ago. Soldered into place by the Airhead tech at my BMW dealer. Battery is less than a year old and connections are tight. Rotor, stator and diode board were replaced 4 years ago with Enduralast II parts.

I put a voltmeter on the bike today and went out. Gen light was working normally starting out. Bike is charging at 14.2 to 14.4 volts, dropping to around 12.9 or 13 near idle. One time during the ride I saw the voltmeter jump to 15.6 volts, just for an instant then it settled back at 14.3. After a stop, the Gen light was out again. I figured I would just ride home on the battery. But, I got to the first stop sign and the Gen light was on. When I pulled away, charging began again. Is it possible for the voltage regulator to go open and then start passing regulated voltage? To catch that, I would have to pull the gas tank and bypass the VR while the Gen light is out to see if the light comes back on, or buy another VR and try that. It also appears to me that the Gen light is staying on longer, not extinguished until the RPM gets above 2,000. That previously went out at around 1,500 RPM. Any other thoughts?

The aftermarket voltage regulators are a dime a dozen. Might be worth a shot to sub a known good regulator and go from there.

20774 said:

The aftermarket voltage regulators are a dime a dozen. Might be worth a shot to sub a known good regulator and go from there.

Click to expand...

I might try to pull the voltage regulator that’s on there and just make sure that the connection is clean and secure. If that doesn’t change anything, then I’ll order a replacement

Another Gen light update

I pulled the VR connector, coated the contacts with dielectric grease and connected it a few times.

The Gen light was working on initial start, and charging was in the range of 14.2 to 14.4 v. At restart after an hour or so, it wasn’t charging, but did start to charge once rpm got above 3K. At restart again at the end of the ride, charging began at around 2.5K rpm and was showing charging at 14.6 and 14.7 volts.

I ordered a new voltage regulator.

Final Update on Electrical Indicator

New voltage regulator did not change the issue.

Yesterday I opened up the front cover to do some testing of the charging system. The diodes on the board tested good, only allowing current in one direction. The rotor showed approximately 6.0 ohms with the brushes lifted.

What I did note was that the front brush appears to have a taut wire lead. The brushes were installed 20K miles ago by the Airhead tech at the local dealership. But the front wire is soldered in place with the wire pointing out to the right, then it runs up and over to the left to the brush. So, it looks to me like the brush is losing a millimeter or two in this extra loop. The rear brush has plenty of slack in the wire lead and both brushes seem to still have enough brush remaining. I tried to push the front wire lead down a little to provide more slack.

A test ride today of a hundred miles, and the Gen light worked fairly normally. Both times I stopped, the Gen light was lit up each time I turned the ignition back on. It still seems like it takes longer for the light to go off once the motor is warmed.

I will replace the brush this week and expect that will permanently correct the problems.

If new brushes are obtained from rick at motorrad Elektrik there will be crimped "eye" connectors obviating the need for soldering. I have some of these new type of brushes.. if you want them sooner, send me a pm or email and we can meet up and I'll give them to you.

robsryder said:

If new brushes are obtained from rick at motorrad Elektrik there will be crimped "eye" connectors obviating the need for soldering. I have some of these new type of brushes.. if you want them sooner, send me a pm or email and we can meet up and I'll give them to you.

Click to expand...

Wow, really nice of you to offer. I ordered those brushes from Rick today. They should be here in a couple of days. Why weren’t brushes made that way a long time ago?

I don't know. But, I'd go a sufficiently long interval between installing the graphite brushes and would be rusty in my "rapid" soldering technique. Thus, I'd usually need to order some extra brushes for "practice". I would be too slow with the soldering and have the braided copper turn into solder wick impregnated with solder - and not flexible. The crimped on "eye" connectors on the braided copper are simply bolted on; this is much, much simpler.

Final Update on Electrical Indicator

I think this problem is resolved by installation of new brushes (only installed one so far) from Motorrad Elektrik.

I loaded up a link to four photos.

It looked like one of the brushes - the front - was on a much tighter wire lead than the rear brush. The photo of the old brushes shows how the front brush was soldered with the lead positioned in the wrong direction, forcing the lead to travel out and around, losing most of the slack.

The new brush has a ring terminator making it super easy to attach to the brush terminal instead of having to solder the new brush in place.

A 20 mile test ride with the new brush installed has all charging back to normal. The GEN light is functioning normally and the Gen light is going out at about 1500 RPM which is the right function.

https://1drv.ms/f/s!Atx-rTuy0GpcggAFVGnZs6149QaA

Great that you got to the bottom of this! Also nice to see the change to the brushes and leads...that was something that stopped me from changing brushes a number of miles ago. Everything has been working OK, but nice to know there's a slightly easier solution.

m_stock10506 said:

I think this problem is resolved by installation of new brushes (only installed one so far) from Motorrad Elektrik.

I loaded up a link to four photos.

It looked like one of the brushes - the front - was on a much tighter wire lead than the rear brush. The photo of the old brushes shows how the front brush was soldered with the lead positioned in the wrong direction, forcing the lead to travel out and around, losing most of the slack.

The new brush has a ring terminator making it super easy to attach to the brush terminal instead of having to solder the new brush in place.

A 20 mile test ride with the new brush installed has all charging back to normal. The GEN light is functioning normally and the Gen light is going out at about 1500 RPM which is the right function.

https://1drv.ms/f/s!Atx-rTuy0GpcggAFVGnZs6149QaA

Click to expand...

Excellent and thanks for the news about the updated parts

The discussion about worn graphite brushes reminds me of the last time I saw Oak at a rally. It was in 2005 in Lima, Ohio in the Airhead tent. A feller pulled up on his R100RT and said that the charging light would not go out. Folks gathered round his bike and soon the charging system was disassembled for inspection.

In this feller's case the brushes were sufficiently worn that the springs could not apply sufficient force on the brushes and the brush was not making good contact with the slip rings. I believe that Oak mentioned a trick that one could use in a pinch. That is to gently lift the spring from the top of the brush and put something of a suitable size (i.e., part of a match stick) atop the brush then replace the spring on the match stick. This will allow the brush to make contact with the slip ring until a more permanent repair can be effected.

At the rally, Rick from MotorRadElektrik was in attendance with new brushes (pre-crimped ring terminator days) and he had a soldering iron and solder. There was a feller in the Airhead tent that was an electronics tech and he did the soldering (nice quick technique). [Of course, with the OP's issue with strain on the connector, the match stick "fix" would not have worked.]

Following is a photo I took of Oak giving a lecture about the Airhead charging system -