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1Back to top Go down   Electrical gremlin Empty Electrical gremlin Wed Sep 09, 2020 5:43 pm

davemadsen

davemadsen
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My 1987 K100RT has been a reliable and trouble free bike for years and many, many miles and I try to do my part in keeping the maintenance current to include keeping most of the switches clean, corrosion free, and slathered in dielectric grease.

Recently the bike has taken to going dead as it idles or, more commonly, as I come to a stop. The engine doesn’t falter, it is as if I hit the kill switch. Up to this point this seems to be a typical short or poor ground (and either of these could in fact be the issue). But I want to mention a couple of things I noticed to aid one of you gurus towards pointing me in the right direction:

The problem occurs once in ever 20 or 30 stops
When the bike dies, the gear indicator goes blank - and then after 10 seconds or so, the indicator comes live and the bike will restart.
And today’s secret clue is this: the low fuel light comes on. The low fuel light has not worked in years and the tank was about 3/4 full (and verified by a fuel gauge and a recent receipt from Chevron).
During the last two occurrences, I refrained from panicking and flipping switches and pushing buttons, rather just I waited ten seconds or so until the gear indicator came live, at which time the bike restarted and I continued on my way. It was during these panick-less stops that I noticed the low fuel light burning. 

The purpose of this post is hopefully get advise from you on where to start, as opposed to spending my time in a direction which doesn’t make sense.

Dave


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Dave
    

2Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Wed Sep 09, 2020 7:54 pm

Arlina

Arlina
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Check the startermotor brushes, should be longer than 7mm.
Place some new ones and I guess the problem should be over.
Leaves you as gremlin as you post this in "buy and sell" Razz


__________________________________________________
Electrical gremlin Eu-log10  K1100RS/LT - R1200RT - R1100RS (RIP) - Cagiva SST 350 Ala Verde - K75LT project - K75 Schurgers - K75S
    

3Back to top Go down   Electrical gremlin Empty Gremlin Wed Sep 09, 2020 11:13 pm

daveyson

daveyson
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I'm reaching, but since the problem has suddenly started and the fuel light has also suddenly started, if unplugging the white wire to the fuel light fixes the problem, that might be a place to look.

It's three quarters full because you looked in the tank,  or at the fuel gauge or both? Maybe alternator brushes wanna look see too.

Wiggle some wires, like say at the instrument cluster or tank, to see if it affects the gear indicator, fuel level light or something.

How's the previous momentary miss with turn signal problem going?


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

4Back to top Go down   Electrical gremlin Empty Gremlin Thu Sep 10, 2020 4:19 pm

daveyson

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Actually, ignore my previous post until you try this; clean the socket for fuse one (top fuse) and replace it with a new fuse, even if it looks good, and see if that makes a difference. It's probably the quickest, easiest check. Probably the cheapest, weakest link in the chain too.

Then do the other fuses. It's a good thing to do, even if you don't have problems.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

5Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Sep 10, 2020 6:46 pm

davemadsen

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Okay. I have a couple of “to dos” and I will report back.

Fuel level was verified...about 3/4 full.

On the turn signal intermittent problem. I have ordered another flasher relay to see if that may be the issue.


__________________________________________________
Dave
    

6Back to top Go down   Electrical gremlin Empty Gremlins Thu Sep 10, 2020 7:13 pm

daveyson

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I was thinking fuse one might be the cause of the turn signal problem too.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

7Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Sep 11, 2020 12:47 pm

davemadsen

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@Arlina wrote:Check the startermotor brushes, should be longer than 7mm.
Place some new ones and I guess the problem should be over.
Leaves you as gremlin as you post this in "buy and sell" Razz
On the chance that I just might learn something, why would the condition of the starter motor brushes have something to do with the bike dying?


__________________________________________________
Dave
    

8Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Sep 11, 2020 6:55 pm

moriarti

moriarti
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On this forum iv read of a few Strange hiccups being traced to the starter,how many Km/years is it since it was serviced.Worth a look and you might learn something you can share with us .


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

9Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Sep 11, 2020 9:44 pm

Dai

Dai
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Because a large amount of the electrical system earths through the starter motor brushes and the starter motor coils. Is why the load shed relay drops out when you hit the starter button and turns the lights and other bits off. Normally pin 85 on the load shed earths through the aforesaid starter bits but when you hit the button, the starter circuit back-feeds 12v to pin 85 and the relay drops out.

Not a terribly good idea on BMW's part but then who knows how much schnapps Hans drank before he designed that system.


__________________________________________________
1983 K100 upgraded to K100RS spec, 1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

10Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Sun Oct 11, 2020 12:32 pm

davemadsen

davemadsen
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I have not died, it just has taken me a few weeks to find the time to address the starter motor brushes. The first thing that struck me was the difference in length. The brush going to ground was 10.2 mm while the brush from the relay was 7.9 mm.

I installed a new Denso assembly and will see if my stalling problem has disappeared. Also, with the OLD brush assembly, the brushes fed from the outer edge while the replacement assembly are ‘loaded’ from the edge nearest the commuter. The functional difference is with the old assembly the wire connected to the brush would restrict forward travel such that the brush would begin to lose positive contact with the commuter as the brush neared 7mm-8mm. The new brush assembly loads the brush from the end nearest the commuter so brush movement is not restricted.

I will post again in a couple of weeks with an update on the stalling.


__________________________________________________
Dave
    

11Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Tue Oct 13, 2020 9:11 am

Holister

Holister
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Had a very similar problem with my 89RT about 6 years ago. I'd pull up to a stop and she'd just stall. It would then just start back up and all was good but it was intermittent.
The problem was very tight exhaust valves. Re-shimmed her and never had that problem again.
You can read the thread here...
https://www.k100-forum.com/t8442-engine-cutout-on-throttle-off


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Electrical gremlin Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

12Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 1:43 pm

davemadsen

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I checked the valves - both intake and exhaust - and they were spot on. Given my problem appears to be electrical (I.e. gear indicator goes blank and speedometer drops to zero), I suspect that valves are not the culprit.


__________________________________________________
Dave
    

13Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 1:57 pm

davemadsen

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Update on electrical gremlin: the problem persists. If anything, it seems to be getting worse.

Following two recommendations, I replaced the starter motor brush assembly and verified the exhaust valve clearances.

One additional observation today is after the bike died the speedometer drunkenly floated to around 1500 rpm before coming back to zero (this was within a second or two after the engine had died and was at a standstill). Also, during one attempt to restart the bike immediately after dying, the idiot lights were lit, but dim. The starter turned very slowly. After waiting maybe two seconds, the bike started normally.

When I feel the bike dying as I slow to a stop it feels differently from a normal decrease in speed - it as if the kill switch was on. Before coming to a standstill, I can quickly bump start the bike and it immediately comes back to life.


__________________________________________________
Dave
    

14Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 3:18 pm

chris846

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Check and Deoxit everything.

You've looked at the likely culprits and not found the problem. So you're at the stage where you just have to eliminate stuff. It'll not be wasted effort, checking and cleaning all the connectors is a very useful thing to do on a bike of this age anyway.

Bad earths tend to be responsible for the really weird faults, so tank off and do a first class job on the frame earths.


__________________________________________________
Sometimes I'm not really Suzi Quatro.
    

15Back to top Go down   Electrical gremlin Empty Gremlin Fri Oct 16, 2020 3:31 pm

daveyson

daveyson
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I'd clean the fuse connections and put new fuses in. That might do it.

I'd unplug the fuel level wire.

I'd unplug the wire from the flasher to the instrument cluster (coil-tacho?)

Sposing the flasher wire is drawing heat (rusty connection, teeny weeny short, plug not fully pushed home,  or loose, sumnat like that) that might explain why it only stalls at idle, why the speedo chucked a wobbly, why you had a flasher related problem, and that.

A lazy way would be a piece of paper on a pin before plugging a connector back.
I guess removing those wires could eliminate the problem, if so then just plug one back in to find which one.



Last edited by daveyson on Sat Oct 17, 2020 2:24 am; edited 2 times in total (Reason for editing : Tacho and typo's.)


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

16Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 3:36 pm

92KK 84WW Olaf

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Also, during one attempt to restart the bike immediately after dying, the idiot lights were lit, but dim. The starter turned very slowly.


Earth issue has been highlighted:
1: Bad earth terminal connection from battery?
2: Bad connection inside ignition wiring or the connection.
3: Bad battery [get it load tested]. 


Does the warning triangle light come its 1 2 or 3 AND does the clock also  go blank, if yes its 1 or 3.


Starter you have eliminated.


A bad relay can eat juice and a bad flasher relay can do just that. Been there.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

17Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 4:03 pm

Laitch

Laitch
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@chris846 wrote:Check and Deoxit everything.

Bad earths tend to be responsible for the really weird faults, so tank off and do a first class job on the frame earths.
+1


__________________________________________________
1995 K75 81,000 miles
Electrical gremlin Usa-lo10
    

18Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 5:10 pm

robmack

robmack
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+1 on checking grounds.

The clock is fed from fuse 3. Fuses 3, 4 and 5 have common feeds. The same circuit also feeds the ignition switch, the load shed relay and the starter relay. The source of power to these components is directly from the battery. I'd be checking the wiring in this area. Check for loose connections on the battery positive and starter relay pin 30. Same goes for loose or intermittent connections on fuses 3, 4 and 5.


__________________________________________________
Robert
1987 K75 @k75retro.blogspot.ca
http://k75retro.blogspot.ca/
    

19Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 7:50 pm

costellon

costellon
active member
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@chris846 wrote:Check and Deoxit everything.

You've looked at the likely culprits and not found the problem. So you're at the stage where you just have to eliminate stuff. It'll not be wasted effort, checking and cleaning all the connectors is a very useful thing to do on a bike of this age anyway.

Bad earths tend to be responsible for the really weird faults, so tank off and do a first class job on the frame earths.

BIG +1

    

20Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Fri Oct 16, 2020 9:15 pm

Holister

Holister
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Electricals doing weird things is a sure sign that there's a ground/earthing issue. In a K-bike the most common issue here is the starter. So it looks like you've sorted that but don't forget to clean the mating surfaces where the starter beds down to the GB casing.

Pretty much nearly everything on a K-bike earths via the main ground point on the frame spar under the tank. You can easily check whether this is working properly by measuring the impedance between a wire on that point and the negative terminal on the battery. You should be reading <5Ω. If >5Ω then test between there and the GB casing and then also between the GB casing and the battery neg terminal. If there's something impeding the current on the earth side then this will tell you where it is.
• The earth connections at the frame can be corroded.
• Earth continuity through the frame to engine mounting points may not be good.
• The earth cable from GB to battery might be physically failing. The strands can stress and start to break at the ring connector.

You can upgrade your earthing system by adding an additional cable from the main ground point on the frame spar to the earth lug on the GB. This bypasses the earth connection through the frame to engine mounts. It's called an Engine-to-Chassis Ground Strap.
Upgrading the battery earth cable to a heavier gauge wire is a good idea also.

I can't see where you mention your battery (may have missed that) but a bad battery will have the same effect. The fact that you can start the bike is no indication that the battery is ok. Nor does seeing 12 point something volts across your battery terminals indicate a good battery. It really needs to be tested under load. Go to a battery shop and get that done even if just to eliminate it from the equation.


__________________________________________________

1989 K100RT     VIN  0097367 (naked)  
1996 K1100RS   VIN  0451808
  Electrical gremlin Austra12    Fuel:  95 Octane
Engine Oil: Nulon Full Synthetic 15W50
Gear Box Oil:  Nulon Synthetic 75W90
    

21Back to top Go down   Electrical gremlin Empty Gremlin Sat Oct 17, 2020 1:24 am

daveyson

daveyson
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" lt's as if the kill switch was on"

Maybe give the kill switch a look and clean.


__________________________________________________
11/1985 bmw k100rt (late model)  Vin. 0090567
 ~120,000 km
    

22Back to top Go down   Electrical gremlin Empty Electrical gremlin Sat Oct 17, 2020 4:11 am

audibob

audibob
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Life time member
+1 on the Kill switch.

My bike started to cut out periodically, although it restarted every time.  My Kill switch was in poor conditon,

so I fitted  a good used unit  and have now done  20k  problem free.

Bob


__________________________________________________
Yamaha 90
Honda CD 175
Honda CB 360 
Triumph T 140V Bonneville
Triumph T150 Trident
Honda CB750 F1
Cz 175
Yamaha XS 750
R 100/7
R 80
K100 LT
K100 LT current bike
    

23Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Sat Oct 17, 2020 6:23 am

moriarti

moriarti
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Should all of the suggestions posted, not identify the problem, there is one other possible cause, Ignition Control Unit.After hours of trying everything,Crazy Frog suggested the ICU and joy of joy problem solved with a S/H unit.Hope you get lucky Very Happy


__________________________________________________
1984 k100 rs red/black VIN  0004449
    

24Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Sat Oct 17, 2020 11:35 am

davemadsen

davemadsen
Silver member
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Yikes! I was hoping to travel and see the world and now I find I will be spending my golden years in the garage. Grounds, grounds, and more grounds...one would thing we were talking coffee!

Going down the proverbial troubleshooting rabbit trail, I read the TPS might be failing and/or dirty and the reader had disconnected his TPS and his (similar) problem disappeared. I pulled off the TPS connector and took a 20 minute ride duplicating the various conditions which I had (earlier today) led to repeated stalling issues. Smooth sailing! This does not mean the problem has been properly identified, only a solution was found.



Last edited by davemadsen on Wed Oct 28, 2020 7:29 pm; edited 1 time in total


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Dave
    

25Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Sat Oct 17, 2020 3:12 pm

mike d

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Be grateful that you don't own a motronic equipped bike as they will not run without the TPS in place.

On your Jetronic model the TPS is but a two position switch to detect 'off - no throttle) and WOT Wide Open Throttle.

Mike

    

26Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Wed Oct 28, 2020 7:28 pm

davemadsen

davemadsen
Silver member
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I mentioned in an earlier post that disconnecting the TPS seemed to resolve the stalling problem - but alas, it has not (although taking the TPS out of the equation has rewarded me with a super smooth engine response around the 2000 rpm point).

The bike stalled this morning and I sat five minutes before the idiot lights came back to normal (rather than dim) and the bike restarted. Yesterday it stalled and I sat two or three minutes waiting for the gremlin to move along. So it seems restarting after stalling has progressed from a second or two to five minutes. So....

I spent this morning cleaning frame and engine grounds (the grounds looked good). The primary frame ground had slight discoloration on the bare metal of the frame. The dielectric grease from past cleanings was still present.

I will have the battery load tested tomorrow.


__________________________________________________
Dave
    

27Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Wed Oct 28, 2020 7:31 pm

davemadsen

davemadsen
Silver member
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@Holister wrote:Electricals doing weird things is a sure sign that there's a ground/earthing issue. In a K-bike the most common issue here is the starter. So it looks like you've sorted that but don't forget to clean the mating surfaces where the starter beds down to the GB casing.

Pretty much nearly everything on a K-bike earths via the main ground point on the frame spar under the tank. You can easily check whether this is working properly by measuring the impedance between a wire on that point and the negative terminal on the battery. You should be reading <5Ω. If >5Ω then test between there and the GB casing and then also between the GB casing and the battery neg terminal. If there's something impeding the current on the earth side then this will tell you where it is.
• The earth connections at the frame can be corroded.
• Earth continuity through the frame to engine mounting points may not be good.
• The earth cable from GB to battery might be physically failing. The strands can stress and start to break at the ring connector.

You can upgrade your earthing system by adding an additional cable from the main ground point on the frame spar to the earth lug on the GB. This bypasses the earth connection through the frame to engine mounts. It's called an Engine-to-Chassis Ground Strap.
Upgrading the battery earth cable to a heavier gauge wire is a good idea also.

I can't see where you mention your battery (may have missed that) but a bad battery will have the same effect. The fact that you can start the bike is no indication that the battery is ok. Nor does seeing 12 point something volts across your battery terminals indicate a good battery. It really needs to be tested under load. Go to a battery shop and get that done even if just to eliminate it from the equation.

Humor me, what is GB casing?


__________________________________________________
Dave
    

28Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Wed Oct 28, 2020 7:38 pm

92KK 84WW Olaf

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Gear box casing, the lug above the gear lever near the coils. The earth terminal from the battery is normally screwed into that lug.


__________________________________________________
1992 K100LT 0193214 Bertha Blue 101,000 miles
1984 K100RT 0022575 Brutus Baja Red 578 bought 36,000 now 89,150 miles
1997 K1100LT 0188024 Wotan Mystic Red 689 58,645 now 106,950 miles Deceased.
1983 K100RS 0011171 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 37,190 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 39.885miles.

Past:
1968 Yamaha 80 YG1
1971 Yamaha 125 YAS-1
1968 Honda 125 SS
1970 Honda CD 175
1973 Honda CB500-4
Honda CX 500
    

29Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Nov 05, 2020 12:07 am

davemadsen

davemadsen
Silver member
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Deox-It’d the connectors on all the relays.
Removed the turn signal/flasher relay (possible problem relay)
Tested each fuse
Deox-it’d the fuses and fuse holder

Checked wires, connections, connectors, and grounds under the tank
Disconnected the speedometer and gear indicator connectors (to alleviate possible problem points)
Cleaned and sanded frame where frame connects to GB. Cleaned bolt, bolt threads, and washer for same.

Slathered (technical term) dielectric grease on all connections, my shirt, and a good pair of pants.
 
The plan is to ride it for a week. If after a week, stalling is only a distant memory, I’ll reconnect speedometer and gear indicator, followed by the turn signal/flasher relay another week down the road.


__________________________________________________
Dave
    

30Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Nov 05, 2020 12:49 pm

davemadsen

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@Holister wrote:You should be reading <5Ω. If >5Ω then test between there and the GB casing and then also between the GB casing and the battery neg terminal.
Measured 0.4 ohms.


__________________________________________________
Dave
    

31Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Nov 05, 2020 5:15 pm

Laitch

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@davemadsen wrote:The plan is to ride it for a week. If after a week, stalling is only a distant memory, I’ll reconnect speedometer and gear indicator, followed by the turn signal/flasher relay another week down the road.
It's likely to stall.  Sad


__________________________________________________
1995 K75 81,000 miles
Electrical gremlin Usa-lo10
    

32Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Nov 26, 2020 2:30 pm

davemadsen

davemadsen
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Resolved!
With some certainty I believe I had a grounding issue. 
While I felt I had done a good job of ensuring my ground points were clean, alas it seemed they were not good enough. My ground point under the tank was good but I think the frame to engine points were the weak point. I removed the 10mm (?) bolts securing the engine to the frame and with a tap and die cleaned the threads. I also ensured the washer and the head of the bolt was just shiny metal. With everything bathed in dielectric grease and torqued to spec, my problems were resolved. 

The various components I took off line as to eliminate possible causes have all been reinstalled or connected and the bike is back to where it should be. 

I want to thank everyone for their input.


__________________________________________________
Dave
    

33Back to top Go down   Electrical gremlin Empty Re: Electrical gremlin Thu Nov 26, 2020 2:38 pm

Point-Seven-five

Point-Seven-five
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A couple of my bikes have a heavy wire(4 AWG if I remember) running from the frame ground under the tank to the ground point on the transmission. I don't like relying on the frame and the engine to provide the ground for all the lights and instruments on the bike. Wasn't too hard to install.


__________________________________________________
Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

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