1st coil no spark

[SJK]

Hi everyone, Hope this post finds you all well. I'm in desperate need to get my pride and joy project running. I bought my K75 1989 model a year ago, this bike was already stripped in pieces but I was told it's a running bike and the motor has just been overhauled. This sounded perfect as I was looking to customize it into a cafe/brat.

After putting all together and investing time and money for the customization, I found the seller was not all to honest.

My latest problem is with the Spark on the first coil. Has anyone maybe had an issue with no spark on just the first coil?

I have checked and swapped around all the spark plugs,coils,leads...but it always stays faulty at coil 1.
I then bought new spark plugs and new coils,no difference.
I sent the ignition PCB in and they said they found faulty components and repaired , but guess what......still no spark on no:1
I did the test on Hall effect sensor with LED bulb and all works fine so guess it's not that
😕

Please has anyone experienced this or does anyone have and idea, your help will be greatly appreciated

[Laitch]

My latest problem is with the Spark on the first coil.

Welcome, SJK.

Do you have a multi-tester and a wiring diagram for your bike's model and year?

[kennybobby]

When you try to crank it over, does the tachometer needle move and bounce?

If not then your symptoms seem like a bad Ignition Control Unit or connection there.  Pull the connector and inspect/clean all the contacts especially pin 14, also the big ground connection to the bare frame under the tank near the ICU.

[SJK]

Hi Laitch, thx. Yes I do have a multimeter and a wiring diagram.why?

[SJK]

Hi KennyBobby, I unfortunately don't have a tachometer , another missing part in my great buy😞...is there maybe another wat to test the Ignition PCB? As I would like to do this my self seeing as I've already had it in for a supposed repair.

[Laitch]

Hi Laitch, thx. Yes I do have a multimeter and a wiring diagram.why?

For one thing, the diagram when enlarged and framed looks great on a workshop wall.

It also helps in tracing continuity and connection problems in the wires running to coil #1, and connection problems in general if an aftermarket instrument has been substituted for the original instrument cluster. It's unclear in your posts whether you've done that.

As kennybobby has indicated, pin 14 plays a big part in function. Aftermarket instrument swaps can be so difficult, some owners may sell off the bike rather than deal with them. Do you have the original cluster or a substitute?

[SJK]

😃yes I'm sure it will make a nice picture framed , and the way things are looking for me I might just put the bike in a glass display box soon as well😂.

I'm really not to sure how original the wires are as it was part stripped when I bought it. I'm thinking of maybe trying be path of installing a new set of wires from ignition pcb to coil1 to hopefully get the spark

[Revrdmark]

In general I hate wiring!! I'm at the point in my project where I have been rewiring in it and my brain hurts! I'm new to these bikes and others can correct my idea who know better. The k75 has three coils I believe (k100 has two) since only one coil is not sending spark and you have substituted it with a known working one it must be a wiring or ICU issue. What I would do is use your light and start at the plug and work backwards through each connection and see if you get a blink at each connection. Electricity is like water ( and other things) that roll down hill. Once you get a blink you know the issue is down stream from there. My assumption is that your ICU is bad or the connections are bad. I wouldn't trust the guy that "fixed it". It would be great if you had another bike to plug it into and see if the problem happened on the second bike.

Even without a instrument cluster the bike should still run. I've had my instruments off for three weeks and started my k100 w/o them 50 times.  Your milage may vary.

These German engineered bikes are starting to make me miss my old '78 Yamaha xs400 with points. Lol took about 5 minutes to trouble shoot that ignition :-)


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