Good afternoon
Yes, there is a cable connecting both coils to the ground point as shown in the photo:



Can you help me with the pin issue? How do I know which are 31, 15 and 1? Can you provide me with some photos of the correct connection?

Thanks

The numbers are molded onto the bottom of the coils next to the terminals.

Good

The coils don't have these numbers, I just identified 15.
But the disconnected brown cables are earth, right? they should be connected to the steel cable that joins the two coils to the earth point, correct? 
Or because you have the other, these are no longer necessary?

Today I was cleaning the electrical terminals in the coil area and the ground point, after I went for a ride and the bike seemed much better, without shaking so much and I managed to reach 150 km/h.
I was enjoying riding the motorbike, but... after a short stop to drink a coffee, the motorbike wouldn't start, it seemed like it had no battery, but it had been charging, weird.
I waited a while and it started again with some difficulty, it seemed like the battery was missing, but it wasn't full. I didn't stop anymore and came home.
After stopping I tried it once again and it stuck well, later I tried it again and nothing.
It stopped making that noise after turning on the key, the starter motor doesn't give a signal and I only hear the noise of the fuel pump when pressing the start button.
Could it be the relay? How can I test?
It's this one?


Well, this bike is killing me...

César Santos wrote:But the disconnected brown cables are earth, right?

No, the cable is doing their job now, but you could do a more attractive job of taping them.   

So tell us, César.  Did you attach the correctly colored primary cables to the correct terminals beneath the coils, and why haven't you posted a photo showing the underside of the coils so we can verify your work?

That is the starter relay. Tap on it with a screwdriver if it isn't working. Sometimes that will get the contacts inside to work. The failure to start could indicate two problems—a worn starter relay and a battery too weak to work properly. You should tell us the resting voltage of the battery and its voltage under load by using a multimeter to check it.

You can get Portuguese subtitles by clicking the Settings icon at this YouTube link.
https://www.youtube.com/watch?v=OiYzmVhgm2s

Otherwise, here it is in American.

Good morning


I've already taken the fuel relay, the starter relay and the starter motor to the electrician and everything is ok.
Fuses all ok.
Battery ok.
The weird thing is that I don't hear that characteristic noise after turning on the key.
Any suggestion?

César Santos wrote:Battery ok.
Any suggestion?
I don't hear that characteristic noise after turning on the key.

My suggestion is to use a description more clarifying than "ok". If everything were "ok", we could all go back to our mochas and bird watching. 

What was the battery's resting voltage and its voltage under load? What is "that characteristic noise after turning on the key." Do you mean when turning the key to "ON" or turning the key to "START"? Describe the noise.

When I say ok, I took the battery, starter motor and both relays to the electrician and he tested them, everything was fine.

The sound I'm referring to is when we turn on the key, not the starter. When you turn the key to ON, the instrument panel lights up and you hear that noise from the fuel pump and system.
Now when turning ON, only the instrument panel light comes on, the rest is silent.

Thanks

If you have a 2-valve K100LT, you should not hear the fuel pump when you turn the key to ON. The pump runs when the starter is turning the crankshaft and when the engine is running, not before then. If the starter has been cranking the engine or the engine has been running and then the key is turned to OFF, the fuel pump will be heard for two seconds then it shuts off.

What year is your K100?

Your electrical contact cleaning should include all relay body terminals and all the sockets into which the relays fit.

My motorcycle is from 1986, but when I turn the key to ON, I always hear the fuel pump.

Weird...

If you can start and run the engine now, do you hear the pump for two seconds after you turn the key to off?

No

César wrote:My motorcycle is from 1986, but when I turn the key to ON, I always hear the fuel pump.
Weird...

What's weird to me, César, is that you keep relying on the opinions of people who have been unable to repair your Brick for the last two years.   It would seem more economical to rely on advice from strangers like me where no cost—except mental anguish—is involved for the opinions.  

To me, there is either a defect within the relay that causes it to deliver current to the pump when it should not, there is a defect inside the ignition control unit that delivers current to the relay when it should not, or a defect in harness wiring behind one of these conditions.

You are getting closer to finding the problem. Keep cleaning.

Good morning,


Solved, it was battery.

It gave signs that it was ok with the electrician's machine, but after checking everything we went back to the battery and despite giving correct values it was out of health.
The battery was new, but the bike was consuming some and as the bike didn't run much, it ended up ruining it.
The electrician corrected the point that was consuming, new battery and it's on...

Thanks for help

I have this recurring thought: a hapless and ever-so-slightly poorly K sat there in the garage being poked and prodded all over the place with screwdrivers and spanners, thinking 'why isn't my owner as reliable as me?'.

Sorry OP, we've all done it  .

Good morning

This weekend I took my first short trip on the K100, 650 kilometers, not all followed.
The bike behaved well, always working well, very reliable.
But the comfort zone is up to 80km/h, between 80 and 120km/h I feel a lot of resonance and vibration and the engine screams a lot...
Shouldn't the bike be an easy bike to ride at 120/140 km/h?
I've been searching the forum here trying to understand if this is normal.
What is your experience traveling, do you feel the same way?

Does the vibration start at the same speed?  Does the speed the vibration starts at change when riding in a different gear?  Or does the vibration start at the same engine rpm?

If the vibration is speed related, I would check these things:

1. How old are the tires?  Are you sure they are properly balanced have no flat spots from sitting for a long time?  Are they inflated properly?  2.5 bar(38psi) in front 2.8 bar(42psi) in rear.

2. Are all the engine mounts tight? 

3. Are the steering head bearings properly preloaded?  Is there any looseness in the steering head?

4. Is there any play in the wheel bearings?

5. Is there any wobble or warping in the brake discs? 

6. Is the transmission end of the drive shaft locked in the proper spot on the transmission output shaft? 

7. Is there any binding in the front forks?  Have they been tightened in the proper sequence to remove any stiction?

The bike shakes from 80km/h upwards.
I continue to think that something is not right, especially because the bike is difficult to climb from 4000rpm, a trip at 100km/h is an effort...

César Santos wrote:The bike shakes from 80km/h upwards.
I continue to think that something is not right.

You are correct. Something is not right. Your mechanic and electrician do not have enough experience with K75 systems to determine what is not right so you either must find somebody who has enough experience, you must learn how to examine and test the motorcycle yourself, or you must replace one part after another trying to make it right. The last choice could get costly.

In Reply #68 above, Point-Seven-five has given you a list of mechanical conditions that can cause vibration. If possible, you and/or a mechanic should try to eliminate each item on the list as a cause of vibration. When all of those suspects are eliminated, you can start examining the engine systems.

Knowing where the bike was originally sold could help in this investigation. My understanding is Switzerland and perhaps other members of the EU have horsepower restrictions on some motorcycles. If it has such a restriction, that could account for both its failure meet your expectations in acceleration and also its low top speed.

Does the vibration/shake start at 80kpm no matter what gear the bike is running in?  This is an important thing to know in troubleshooting because it would help determine if the cause is in the engine or in the frame/wheels.

Laitch has a good point about the engine power possibly being limited.  Perhaps some of the European members can check in with some information on how the power output is limited.  I suspect there is some sort of throttle limiter that is installed to prevent the throttle from being opened all the way.

Good afternoon,


I know little about the history of the bike, I bought it in Germany, but its registration there is from 1993, the bike must have been imported, as its speedometer shows miles.
The motorcycle in Germany was serviced at BMW, I have some invoices and the engine seems healthy, always works well and consumes neither oil nor water.
The gearbox is fine, only between 4th and 5th gear sometimes it stays in neutral, I always have to pull the selector up very well.
I have already placed EV14 injectors, new spark plugs, spark plug wires and a fuel filter in my hands.
The mechanic already changed the shaft and seal of the water pump that was pouring and a general inspection (change of liquids, oil and filter).
I already bought the bike with this problem, it goes up to 4rpm but causes a lot of vibration and speeds above 120km/h are almost impossible.
The mechanic I have, I've only known him since I bought the BMW, he was supposedly one of the best in the area when it comes to old BMWs, in fact, he has N in the workshop, but 2 times the bike there was with the same complaint and it came the same way, I've given up.
Hence my search for a solution to the problem, I don't want to give up the bike because I like it, but it's not easy.
From what I read, I should also look at the TPS, air meter and vacuum tubes, I'm completely lost on these topics... And I'm going to measure the coils again.
Thank's for everything

César Santo wrote: And I'm going to measure the coils again.

Point-Seven-five has asked you several questions in Post #68. Do your best to answer them.

The fuel injectors you chose are for larger engines. Why did you choose them?

In response to Post 68.

1. The tires are new and are calibrated and at the correct pressures, originally measured. With the old ones, the bike had the same;
2. The engine mounts are all tight;
3. I have no clearance in the steering head. What do you mean by preloaded bearings?;
4. I don't have any clearance on both wheels;
5. The discs have no clearance and do not appear to be warped;
6. How do I check this? Do I have to open the axle?;
7. I don't have any connection between the forks, it's original and appears to be well assembled and tight.

Thanks

Good...
Yesterday another day in the search...
The vibration starts at 80km/h and so on, in any gear.
Since the tires are new and the wheels are calibrated (I'll do it again), I went to analyze the rear brake and transmission.
The brakes are ok, pumps loose, no problems.
The transmission is ok and looks good, I'll take the opportunity to put some grease on it .
What aroused some curiosity in me is the conical group, as it seems very "stuck" to me, I'll attach a video so you can give me your opinion.

It is without the drive shaft



Thanks

César Santos wrote:What aroused some curiosity in me is the conical group . . .

Conical group = rear drive 

There is a filler plug on top of the rear drive. Remove it. There is a drain plug on the bottom of the rear drive. Put a small pan on the floor beneath it. After you have removed the filler plug, remove the drain plug and tell us how much fluid drains into the pan. The rear drive should have 0.25L within it when correctly filled.

César Santos wrote:The vibration starts at 80km/h and so on, in any gear.

This confirms for me that your problem is in the wheels, frame or suspension.  First thing I would do is double check the balance and runout of the wheels. 

I install and balance my own tires.  This allows me to take the time to get them perfect.  One thing I found a few years ago was that the cast wheels on these bikes can have a heavy spot that often doesn't align with the tire valve.  Depending on how far away it is, it can make balancing a bit challenging.

I now check my wheels without the tire and mark the heavy spot and that is where I put the tire dot.  This has helped make balancing easier, as well as making the bike run smoother at speed.

As far as runout, rotate the wheels and watch closely for any wobble in the rim or inconsistency in how the tire sits on the rim.  It doesn't take much to make the bike shake.

CS,
just a thought… aging fuel line collapsing and starving the pump? 
under heavy acceleration.
Good luck

How is the clutch plate?  Possibly slipping or out of balance?  

To check you will have to remove real wheel, final drive, gearbox, etc.

Good afternoon

The rear group is ok, the fluids are clean.
The clutch doesn't slip, how do I know it's out of balance?
The fuel line looks fine to me, but...

Thanks

Good afternoon

And my search for vibration continues...
The conclusion I reach is that it is evident both when moving and stopped, it seems that it is associated with a certain RPM.
Could it be an alternator bearing?
Suggestions?

Is there vibration if you are coasting in gear with the clutch hand lever pulled in, or when the engine is not in gear when coasting or idling?

If the vibes are the secondary vibes from the engine then you can check if it's smoother in the upper rev range. But the Ev14 injectors do need to be the smaller flowing items or you'll flood the engine above 3000rpm, Item number of 0280.158.200 should be the smallest flow rate injector for 3bar. These bikes are notorious for rich running. and they bog down when accelerating, so best to go back a gear or two and rev it around 5 to 6k in the gears to keep it on the boil. There you will experience your bike's running performance. You can't lug these old girls around much in the lower rev range. 80kph is basically third gear.

Good morning


If the motorcycle is traveling at 100 km/h the vibration is very present, if you press the clutch the vibration stops.

Regarding the EV14 injectors, I don't think it's related, as the same thing happened with the originals.


Thank you for your help

Syncing the throttle bodies reduces K100 vibrations.

César Santos wrote:If the motorcycle is traveling at 100 km/h the vibration is very present . . .

duck wrote:Syncing the throttle bodies reduces K100 vibrations.

After you synchronize the throttle bodies, you can check off items on this list, César.