BMW K bikes (Bricks)


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1Back to top Go down   K100 starter problem Empty K100 starter problem Tue May 30, 2023 8:51 am

JET

JET
active member
active member
I have a problem starting my 1986 K100 RS. I recently replaced the O-rings on the fuel injectors, then started the bike in the workshop (started easily), ran it for a few minutes to check for fuel leaks, and all was OK. When I next tried to start the bike a few weeks later, the starter would crank the engine for one slow turn then disengage on each press of the starter button. If the starter button was held down, it would cycle through one slow turn, disengage, then another slow turn, disengage and so on. On a single occasion, it spun normally for a few turns, almost started, but the reverted to the slow single turns. Plenty of fuel, fuel pump running and the battery fully charged (13.4 volts).
Any ideas from the forum greatly appreciate.

    

2Back to top Go down   K100 starter problem Empty Re: K100 starter problem Tue May 30, 2023 9:17 am

Dai

Dai
Life time member
Life time member
I'd still suspect the battery. Charge it fully overnight, then leave it for the following day to disperse the surface charge. That willl give you a better idea of the retained voltage. If it's above about 12.8 volts, the battery should (in theory) be okay. Try starting the bike and after a few attempts, check the battery again. Contrary to common opinion, they can just die overnight with one or more lead plates collapsing for no apparent reason.


__________________________________________________
1983 K100 naked upgraded to K100LT spec after spending time as an RS and an RT
1987 K100RT
Others...
1978 Moto Guzzi 850-T3, 1979 Moto Guzzi 850-T3 California,1993 Moto Guzzi 1100ie California
2020 Royal Enfield Bullet 500
    

3Back to top Go down   K100 starter problem Empty Re: K100 starter problem Tue May 30, 2023 9:34 am

firstle

firstle
Life time member
Life time member
battery can read correct voltage and still be shot , try and jump start off a car etc just to make sure .

    

4Back to top Go down   K100 starter problem Empty Re: K100 starter problem Tue May 30, 2023 9:42 am

Rick G

Rick G
admin
admin
It sure sounds like a voltage problem to me.
Check the voltage at the battery terminals when it is cranking, it should be above 9.2 volts. If the cranking voltage is almost the same as standing voltage when it is slow to crank check the earth connections at the gearbox and the terminals on the starter relay and battery. Clean them back to bare metal that is no corrosion.
If the voltage is below 9.2 volts the ignition and engine fuel injection modules will not work. A good battery will read over 11.5 volts when cranking. The Ks are very fussy about battery voltage especially the ABS ones. Low battery voltage can and often does cause the starter relay to weld the contacts causing a bit of panic until the battery can be disconnected.


__________________________________________________
"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 (crashed I lived it died) 1999 K1100 LT.
    

5Back to top Go down   K100 starter problem Empty Re: K100 starter problem Tue May 30, 2023 10:14 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
+1 on cleaning the battery and ground connections.  Do that before any other troubleshooting activities. 

If cleaning the connections doesn't fix the problem, pull the battery and have it load tested.

If the battery checks okay and the connections are clean and tight, the problem may be burned contacts in the start relay.

If the start relay is good, pull the spark plugs and see how the starter spins the engine.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

6Back to top Go down   K100 starter problem Empty K100 starter problem Wed May 31, 2023 6:19 am

JET

JET
active member
active member
JET wrote:I have a problem starting my 1986 K100 RS. I recently replaced the O-rings on the fuel injectors, then started the bike in the workshop (started easily), ran it for a few minutes to check for fuel leaks, and all was OK. When I next tried to start the bike a few weeks later, the starter would crank the engine for one slow turn then disengage on each press of the starter button. If the starter button was held down, it would cycle through one slow turn, disengage, then another slow turn, disengage and so on. On a single occasion, it spun normally for a few turns, almost started, but the reverted to the slow single turns. Plenty of fuel, fuel pump running and the battery fully charged (13.4 volts).
Any ideas from the forum greatly appreciate.
Thanks for the advice everyone.
I'll work through the suggestions and see how I go.
Much appreciated.

    

7Back to top Go down   K100 starter problem Empty Re: K100 starter problem Wed May 31, 2023 7:52 am

Point-Seven-five

Point-Seven-five
Life time member
Life time member
One last thing.  Have you checked the brushes in the starter motor?  They can be worn to where they don't make good, reliable contact anymore.


__________________________________________________
Present: 1991 K100RS "Moby Brick Too"
 
Past:
1994 K75RT "Ilsa, She Wolf of the SS"
1988 K100RS SE "Special Ed"
1994 K75S "Cheetos"
1992 K100RS "Moby Brick" R.I.P.
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

8Back to top Go down   K100 starter problem Empty Re: K100 starter problem Wed May 31, 2023 6:18 pm

MartinW

MartinW
Life time member
Life time member


__________________________________________________
1992 K75s
    

9Back to top Go down   K100 starter problem Empty Re: K100 starter problem Thu Jun 01, 2023 3:12 pm

Arlina

Arlina
Moderator
Moderator
Measure the voltage on the battery when you try to start, a bad battery exposes when the voltage drops under 10.
Also clean the earthline on the gearbox (left side).


__________________________________________________
K100 starter problem Eu-log10  K1100RS/LT - R1200RT - R1100RS - Cagiva SST 350 Ala Verde - K75LT project - K75 Schurgers - K75S - K1100RS - K75RT - K75C
    

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