BMW K bikes (Bricks)

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1Back to top Go down   Hall Sensor woes? Empty Hall Sensor woes? Sat Jun 28, 2014 11:15 pm


Platinum member
Platinum member
Hello everyone,

This is in regards to a 1992 k100rs

Well, everything was great for the last 6-7k miles.  Today, I turned the bike on to warm up while I put all my gear on.  Usually it's idling for about a minute before I take off.  I pulled out of the driveway, began accelerating, and the bike died at probably around 4,000 RPM.  I tried to start it back up, but there was no power.  Still coasting, I turned the key off and back on.  The dash lights came on, but were very dim.  I ended up pulling to the side of the road to check things out.  Once pulled over and stopped, I tried the key again and this time had full power.

I still pulled the battery cover off to check the terminals.  The positive terminal was a little loose but had full contact and was still resistant to me moving it around.  The negative terminal was fine.  So I tightened it up, the bike started just fine, and ran normally all the way home (20 mile freeway ride).  I believe that if the issue was truly the battery, the dash lights would not have come on so dimly like that.

Now, I seem to have terrible luck with Hall Sensors.  I went through two on my old k100, and have gone through one on this k100.  I wonder if this was due to a failing Hall Sensor.

Over the passed couple weeks, I noticed random very slight and instant drops in power that lasted no more than 1/4 of a second.  I figured I couldn't do anything about it till it got worse, and now I'm here!

I recall reading awhile back that the Hall Sensors are quite simple and can be made with elements that are readily available from places like Radio Shack for a few bucks, (using the BMW back plate of course).  I'd be interested in doing this instead of spending another $100 for a used Hall Sensor or $400 for a brand new one.  So, does anyone know exactly what I would need, or have a how-to on making a Hall Sensor?

Thanks in advance!

1968 BSA Lightning
1991 BMW K100RS 16v with K1100LT fairing

2Back to top Go down   Hall Sensor woes? Empty Re: Hall Sensor woes? Sat Jun 28, 2014 11:38 pm

Rick G

Rick G
A loose battery terminal will do that.

"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama

Bikes 2004 K1200GT 1998 K1100 LT, 1986 K75 GS.

3Back to top Go down   Hall Sensor woes? Empty Re: Hall Sensor woes? Sun Jun 29, 2014 2:36 am

Ghost who rides

Ghost who rides
Life time member
Life time member
Or a dicky ignition switch will give a momentary cut out.

1986  K 75 C   2nd owner 187,000kms showing .
1987  K100RT  Police repainted, rough and unloved.

4Back to top Go down   Hall Sensor woes? Empty Re: Hall Sensor woes? Sun Jun 29, 2014 3:48 am

92KK 84WW Olaf

Life time member
Life time member
Sounds nore like a power supply issue than Hall sensor. No power to restart and weak lights says it. Check the battery connections and the earth connections and as said the ignition can go faulty but check the connections first. I would check the battery too for what its worth.

I am not sure of the wisdom of turning the bike on to warm up and then leaving it running. That can also drain the battery as the alternator doesnt charge the battery when you do that so you are actually draining it to keep the engine running. If the battery is poor this can drain it quickly. It would seem to be a case of fire up and ride off.

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 0011157 Fricka 606 Alaska Blue 29,495 miles Damn K Pox Its a Bat outta Hell Now 54,800 miles. 
1996 K1100LT 0233004 Lohengrin Mystic Red 38,000 miles currently 42,640 miles.
1983 K100RS 0004449 Odette 55,000 miles. Sprint fairing

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

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