Where to start

[Tom Menard]

After 45 years of riding and wrenching on Harleys I switched to a  1988 BMW K100.   Love the bike but went out to start it and nothing happened when I turned on the key.  I can jump to the switch from the battery and it will start. Assuming the switch is good and with little knowledge about BMW can someone tell me what the first step would be to track down this problem.   I just found this site and this is my first post.  Nice to know you guys are out there.   Thanks

[TimTyler]

Welcome, Tom.

Have a look at this http://hrsbstaff.ednet.ns.ca/bvogel/K100/download/bike-wont-start1.htm

[johnny]

greetings tom menard...

just wanna make sure we know what you gotts...

so... moto on center stand... side stand up... in neutral... kill switch in the run position... key off...

turn key on and what do you have...

headlight... tail light... brake light from front lever... brake light from rear pedal... turn signals... instrument cluster lights... gear postion...

press start button and what do you have...

lotts goes on here... the more info the better help you will get...

j o



yoy turn the key on and what do you have... headlight

[Inge K.]

Sounds like your ignition switch needs to be dismantled and cleaned, quite common problem on old K's.

To verify, mesure the voltage at the ignition switch connector with the ignition on.
Measure at both the red and green wire, and you should read the same voltage...if OK.
Or Connect the probes to the red and the green wire, you should read 0,0....if OK.

http://technik.flyingbrick.de/images/6/6f/61_zuendschloss.pdf

[Tom Menard]

Looking at it now, everything checked,kill switch etc.    When I turn the key on I get nothing at all .  I'm don't have a volt meter but will pick one up today.  However when I run a test lite from the the red wire on the ignition switch it lites up as well as when I run from the red  to the green wires,    starting to sound like the switch the more I think about it but as my wife informs me I'm wrong on a regular basis.     Also just wanted to thank you all for your help . Glad to find this site.

[Inge K.]

When the difference in voltage is as much in this specific case, a test light can be used.
Again test with the ignition on...with the test light connected to the red wire, it should
have normal brightness....when connected to the green wire it should be much weaker.

Another way to verify if the ignition switch is the problem....disconnect the ignition switch
and jump the red and green wire at the harness connector.
With ignition on all should function as normal, exept tail and park light.

[Tom Menard]

With test lite to red wire and ground , very bright. green to ground 0,  jumping red to green lite bulb dimmer but everything lites up, fuel pump working etc.   ???????

[Inge K.]

With test lite to red wire and ground , very bright. green to ground 0,

This verifies that the ignition switch is the problem, if the test was done with the ignition on and the test
light connected between the green wire and ground.

[Inge K.]

Return to Tim Tyler:

[Tom Menard]

Finally I might be able to sleep tonight, thanks to everyone for your help, great site good people