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Help with K75s Bike

3K views 3 replies 4 participants last post by  GT5_33 
#1 ·
My problem: bike won't start most of the time and if it does, it may cut off and never start again for long time.
More info: It is a 1988 BMW K75s with 42, 000 on it. I have had it 1 year now. Also wanted a k bike and now I am wondering. I have a Susuki 800 intruder that gives me no trouble, anyways i ramble. Problem started after I stopped at Mall to get something(i know majorly bad mistake) then when I came out bike would turn over and try to start but act like it was flooded. I call friend to give me a ride home so I could arrange for bike to be picked. Upon arriving back 2 hours later it started and I bee-lined home. On the way home it cut off and I thought not again, but it cut back on and I returned home. In the mean time it ran O.K. still very hard to start but at least it did start Week later I took it on the interstate for a ride to the next town, and it just died on me (cut off) I tried to start it and it would turn off and act like it wanted to but there was a force at work more powerful then the K-bike. I had it towed to the nearest place that would work on it, everyone refused and BMW dealer far away and $$$$. He trouble shot it and did the required test the of fuel pressure, plug spark, ht leads etc. Stated that evrything checked out but it still acted funny, he suggested I buy a good battery $100.00 that it if battery or cell was bad or damaged and wouldn't allow full charge then bike would not start of cut off at times. Put it in bike seemed to start and run, took it home the next day bike acted the same way. I put new plugs into it cleaned and check ground, tested HT leads, un hooked throttle position switch. But bike still hated me and tried but won't start. I have several options but all could cost lots of money and may not fix it, I am also ready to take to BMW dealer and incurr the cost that I know will be high.

Any idea's from anyone, AI notice that a lot of you really know your k-bikes and how to address them. Any help would be greatly appreciaited. Also I noticed on a post that someone stated that there should be 2 ground wires from the battery, I can only find one that goes stright to chassis, and no other wire exists, either dangling, cut , or burn. There just isn't any.

I tried to be through in my explaination, but will check often to see if further details are needed by me...............Thanks Jeff :hanged
 
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#2 ·
Couple of thing come to mind that would cause this. Ignition (key) switch or the kill switch. When the bike cuts out, do you notice any lights coming on? If I recall correctly, the lights don't come on if the ignition switch is intermittant, but the lights come on if the kill switch is suspect. I don't remember if there is a ignition interruption switch on the kickstand, as the clutch cable is supposed to retract the kickstand. You didn't mention any of these being checked out, so they may be a place to investigate.



 
#3 ·
LED's

For my customers with intermittent ignition problems I wire up some 12V leds. I install three at the coil. One for voltage and two that flash (yes I know that you can do it with only 2) with the coil signals.

This way when they call me from the cell phone we can diagnose it on the spot.
Dark - no power (trace positive backwards from coil)
Constant on but no flashing two - signal is gone - check the pulse modulator or pickups.
LED's cost less than a buck

The old Johnny 3 LED setup - It should be factory -but its not

I never ride an endurance event without this setup
 
#4 ·
K100rt

I had a 1985 K100RT which had the same type of problem. On one occasion I noticed if I wiggled the key while in the on position the engine would start. I took the key switch out of the bike and took it apart. Noticed some corrosion. Cleaned the parts, made sure all items were secure and put the switch back together. Never had another problem. Hope this helps.
 
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