MOTOBRICK.COM
TECHNICAL MOTOBRICK WRENCHING In Remembrance of Inge K. => The Motobrick Workshop => Topic started by: ChrisB on October 27, 2018, 09:02:08 AM
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Hi All--
I'd like to start by saying how much I appreciate this forum. It's been invaluable to maintaining my 1990 K75s currently with 72k miles.
That said, I've searched the forum and the web for an issue similar to what I've been experiencing without luck. I'd appreciate hearing the board's opinion of where I should go next.
As the subject says, I'm currently experiencing a stalling failure characterized by the alternator light, starting with a dim glow, gradually over 1 or 2 minutes glows brighter and brighter until the bike stalls. Once the bike stalls it will not start again until the ignition switch is cycled. Once I turn the ignition on and off again the bike will start immediately. This happens while idling on the center stand, as well as while cruising down the highway. Note that most of the time that the bike is running the alternator light is completely off. Sometimes it glows dimly but does not progress from there and the bike continues running.
My attempts to resolve this have included: jiggling the ignition switch and wiring harness at accessible points while the bike is idling, with no failures generated. I've also replaced the ICU with a cheap used ebay unit, and the alternator brushes/voltage regulator with a new unit from Motorad Elektrik. It seems a little better after these parts were replaced--the stall occurring less frequently with fewer back fires while running, but the alternator light gradually increasing in brightness until stalling seems more pronounced. No repairs or work had been done to the bike for at least a year before this started. The CDI was replaced with a used unit a couple years ago. Same with the fan.
I hate electrical problems and I'm really at a loss as to where to go next in attempting to resolve this. I'd really appreciate any suggestions folks may offer.
All the best,
-Chris
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Do you have heated grips or any other accessories? I had a problem somewhat similar to yours related to a bare wire in the throttle side heated grip. It did a slow short that resulted in a blown fuse #1 and the alternator light coming on. That leads to a second possibility, that you may have a bad fuse in the #1 position. Try cleaning the fuse block with DeOxit and installing new fuses.
How old is your battery? Have you cleaned all your grounds?
The ignition switch is also a common cause of similar problems. There are instructions here that tell how to disassemble and clean it.
http://www.motobrick.com/index.php/topic,4909.0.html
BTW, where is your kitchen table located? Just curious.
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Thanks for your reply Mr. Gryphon.
There are no accessories and this is a non-ABS bike. The battery is 1.5 years old. That the alternator light gradually grows brighter until the bike stalls, and that the problem immediately is resolved by cycling the ignition switch, makes me lean toward a more occult problem than a fuse or shorting issue, but I'll take your suggestions under advisement and clean the fuse block and ignition switch.
My kitchen table is located in quaint and scenic but slightly gritty Graniteville, Westford MA, former home of the Abbot Mill, once the world's largest manufacturer of worsted wool.
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+1 to Gryph's suggestions.
Please verify that your kitchen table is located in your kitchen. That's important information for the site's global positioning software.
Check that the battery post connections, the battery ground connection on the transmission, the under-tank frame ground connections, the alternator electrical connection and the ignition switch connector under the tank are clean and tight.
Hating work that needs to be done is futile. Own an electronic multimeter and learn how to use it; otherwise, learn how to earn enough money to pay somebody else to do the work, if you can find somebody who knows these old bikes and wants to be bothered working on them.
Please post some photos of your bike and let us know how many miles are on the odometer, how long you have owned it, and how many miles you have ridden it. We enjoy seeing these bikes infesting their various locales.
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Thanks for the additional suggestions Laitch, I will implement them.
Futility is my default posture, especially with regards to work! And I'll post photos soon, although I can't understand why anyone would enjoy looking at a K75s. I'm just happy that I can't see it while I'm riding it.
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it does sound like a short, my first thought was something grounding on the positive battery terminal (battery hold down?) I'd probably pull the tank and look for some bare wire or something charred.
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Futility is my default posture . . . I can't understand why anyone would enjoy looking at a K75s.
Your empathy skills need a tuneup, too. :giggles
Just consider photos a consultation fee payment, if that helps.
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Personally, I never get tired of looking at bricks, as long as they still have the rear frame loop and most of the original bodywork. It's nice to see how the fleet is holding up.
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Personally, I never get tired of looking at bricks........
Me neither, depending on the age and body of course.
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Please. I'm trying to work here. You folks will be disappointed, my motorcycle bears only a passing resemblance to that. And it stalls while I'm riding. Also while I'm not riding.
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So I removed the seat, tank and battery and cleaned all the suggested connectors and then some:
- fuses and fuse block
- ground at trans and under tank
- ignition switch wire connector
- ignition switch through key hole (set screw could not be removed to disassemble switch)
- battery terminals
- alternator connector
- starter lead
I did not see any frayed or burnt wires during all of this.
I allowed the bike to idle while I picked up the tools. The alternator light was perfectly dark for quite some time then just before the radiator fan kicked in the alternator light began to glow. The glow did not change at idle but got brighter as I fed in throttle especially above 3k rpms. As I let off the throttle and the revs dropped all the lights on the bike that I noticed (neutral and brake indicators in the dash, headlight, alternator light) flickered briefly and the alternator light returned to its dim glow.
Just before the fan kicked in the alternator light went completely dark. Just as the fan stopped the alternator light began to glow again. I'm thinking this may be a coincidence because when the fan kicked in the 2nd time the alternator light just continued to glow. The bike did not stall through all of this. Finally while the alternator light was glowing I shut off the ignition then restarted the bike. The alternator light remained off. This feels similar to my experience that when the bike does stall the ignition must be cycled before it will restart. I stopped the experiment at this point.
I should mention that when these issues first began I tested the Hall effect sensor by letting the bike idle and using a heat gun on it. I heated the sensor until it was too hot to touch without the bike exhibiting any bad behavior.
Also, last summer I had the alternator out to check the monkey nuts, which were fine, and disassembled and cleaned the starter, just before a 5k mile trip that went off without a hitch. Since then I've cycled the starter backwards a couple of times.
Any more suggestions I'm all ears. I have some time tomorrow to work on it and take it for a test ride but I think that's going to be about it for some time.
Thanks to all who have replied so far! Futility wins for today!
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- ignition switch through key hole (set screw could not be removed to disassemble switch)
Futility wins for today!
You cannot assess the function of the ignition switch nor can you clean it through its key hole. You cannot assume it isn't part of the problem just because you can't disassemble it. Keep trying. Warm the case with a heat gun or hair dryer, add some liquid wrench, wait then try again.
Testing wiring for continuity would seem to be somewhere in your future.
Futility won? Hah! We'll all know futility won when you post your moto for sale.
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If I recall, that set screw is sealed with red paint(or is it that damn red Loctite?). You need to clean it out of the hole before the screw will turn. The slot for the screwdriver blade needs to be cleaned out for a good fit with an unworn blade. Laitch's idea of heating may help. Heating the screwdriver blade to heat the screw may also help.
You gotta get in there to clean out those contacts. Don't give up so easily here. It's time well spent.
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Thank you both. I will put more effort into disassembling the ignition switch tomorrow.
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Since I'm going to have to get under the tank again to release the ignition switch wiring from the harness, are there any tips for removing the tank without getting gas all over my hands and the engine? The bike invariably spews about an ounce of gas from the rail feed line, and at least a few drops from the return line. I end up smelling of gas the rest of the day.
Also, while I'm under there, any thing else to test? Laitch, you mention continuity testing. Suggestions for focusing my efforts? Because if I'm going to have to test the whole wiring harness then the bike is for sale (or junk).
What causes the alternator light to glow? Low voltage?
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Please read this post. It is from a guy that seems to understand how things work. At least the explanation of how the alternator light works is the same I learned at Escuela Industrial Superior, in my native Santa Fe, Argentina.
Enjoyed the brick .... picture by the way.
Alex G
https://www.practicalmachinist.com/vb/general-archive/alternator-idiot-light-78415/
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ChrisB... after digesting Laitch's & Gryph's recommendation on using said heat gun etc,., an additional advisement would be to realize you're turning a "thread-locked" screw out of a plastic receptacle which is the switch base, and if you're are not insanely careful you will crack this 2 1/2 decade old POS and then you'll need to obtain another. SLOW and careful is the key.. once out, you'll leap for joy to then realize how filthy your switch is...Have Fun!!!
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Thanks to everyone who offered help and suggestions. AlexG's link in particular seems right on point with the problem I'm having. Unfortunately this morning after a couple hours effort and a 20 mile ride the problem is not reproducing. Other obligations indicate that I may be done for the season. I've got 1 more ride planned to top up the tank before winter storage and if the problem does not reproduce then it will have to wait for spring.
Again thanks to everyone!
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Thanks to everyone who offered help and suggestions. AlexG's link in particular seems right on point with the problem I'm having. Unfortunately this morning after a couple hours effort and a 20 mile ride the problem is not reproducing. Other obligations indicate that I may be done for the season. I've got 1 more ride planned to top up the tank before winter storage and if the problem does not reproduce then it will have to wait for spring.
Again thanks to everyone!
OK
Reading the link it appears it works similar to the BMW Airhead charging system. I worked on something like that this weekend on an Airhead.
Please update us as to the possible solution.
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So I just wanted to update everyone on the current status of this issue which is: not reproducing, possibly self-healed.
Based on the explanation of the alternator idiot light from Alex G's link (thank you!), I dug into the wiring between the alternator output and the battery positive terminal. No issues were found. Idling on the stand did not reproduce the issue and neither did several 20+ mile rides. Measured voltage drop between the alternator output and battery positive terminal was 0.3v but of course the problem was not reproducing. Maybe all the wire wiggling and terminal tightening reestablished a good electrical connection.
For personal reasons my riding season is over for this year. Thanks to everyone who offered suggestions, it's much appreciated.
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Thanks for posting the update.
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So I just wanted to update everyone on the current status of this issue which is: not reproducing, possibly self-healed.
Based on the explanation of the alternator idiot light from Alex G's link (thank you!), I dug into the wiring between the alternator output and the battery positive terminal. No issues were found. Idling on the stand did not reproduce the issue and neither did several 20+ mile rides. Measured voltage drop between the alternator output and battery positive terminal was 0.3v but of course the problem was not reproducing. Maybe all the wire wiggling and terminal tightening reestablished a good electrical connection.
For personal reasons my riding season is over for this year. Thanks to everyone who offered suggestions, it's much appreciated.
Good check, measuring voltage drop is the best way to check for resistance in a circuit. Many times a simple check with a meter will show continuity while the connection is only a single strand of wire or has significant corrosion at the connection.