Hi everyone

I recently attempted to recharge my battery using a battery charger (1600ma charger). after removing the chatger from the battery I pressed the starter and the motor turned over a few times. I then replaced the fuel filter. I then recharged the battery but the motor would not turn over when the starter was pressed. I could hear the starter engaging a few times but the motor did not turn over. i decided it was a faulty battery. i left the park lights on to try and drain the battery completely, thinking it would be recharged later on. The following morning I tried to start the bike. the battery had not been charged. when i preseed the starter, there was a clicking noise which repeated itself every few seconds. (only if i held down the starter switch). If i switched on an indicator light, the tacho needle would move in sync with the indicator light!!!! I attached jumper leads to a car battery and when I tried to start the bike, I could only hear the starter engage (clicking noise?) but the motorwould not turn. bike is a 1984 k100.
any suggestions would be appreciated.

It seems to be an issue with your starter.
Please read the following post
A bad starter will create all kind of crazy electrical problems.

Bert

Hello Gabriel,

Bert is 100% correct. I have same experience recently. My bike is 1984 K100RS, originally exported from Germany to Australia

Firstly, you must have a good & strong battery when you want to start the bike. If not, you will have numerous electrical problem, among others is dash board lights are all OFF. NEVER start the bike with weak battery. You can re-set the electrical system by removing the battery for about 10 minutes.

If you are ready with a good & strong battery, then you you can start the bike. If the stater still doesn't turn, you can take out the stater motor, check it - jump start. If it works outside, then you can re-install it.

Cheers.

Only point I would make is when you have diagnosed the problem down to the starter, if it runs when removed from the bike still give it a really good check over and clean and lube. I also believe one should seriously consider replacing the brushes if worn since if it played up once it will do so again and taking it out is fiddly enough to be a - do it once do it right sort of thing.
Regards,
K-BIKE

My bike is running well now. It starts every time and any time

Ya gotta be happy about that!

hi.
Yesterday I removed the starter from the motor and opened it. I was surprised to find it reasonably clean. The brush holder plate was in excellent condition. Both brushes were approximately nine to ten millimetres in length. My understanding is that the terminal is insulated from the rest of the starter motor. I used a multimeter to test this statement.
I decided to test the armature, which I removed from the body. I set the multimeter to test continnuity between pairs of segments. I found that there was continuity between all of the segments! I then tested for continuity between the segments and the armature core and found that there was also continuity between all of the segments and the armature core.
according to the haynes manual, the starter motor terminal is insualated from the rest of the starter motor. I don't understand how this can be true, when the commutator segments on the armature have continuity between the segments. I also tested the segments on the end of the armature where they make contact with the brushes. I noticed there was continuity between the commutator segments. The terminal is insulated from the brush holder plate but when the cover is replaced and the brushes make contact with the segments, the circuit is complete and the terminal is no longer insulated from the starter motor body!!!!
is there any tests I can perform to determine if the starter motor is functioning. I have a supsicion that the segments should not have continuity between pairs. This could explain the electrical gremlins I have been experiencing recently.
any suggestions would be greatly appreciated.
regards gabriel

Hi Gabriel,
The procedure BMW has for testing the starter is to measure the voltage on the battery whilst running the starter to ensure it is above 8 volts if below that the battery does not have full capacity (their words). Note down the exact value you measured. Then place the meter leads onto the positive pole of the starter motor and the earth of the starter and measure the voltage whilst cranking the engine. Note the value down if the two measured values differ by more than 0.5 volts the starter is defective (again their words).

Now all that BMW stuff said the Valeo starter motor is a simple device with permanent magnet poles in the starter and a commutator and brush holder assembly. When it is in the bike with the starter solenoid cable disconnected testing with an ohm meter between the positive pole and the body or ground will indicate a low resistance because the power from the meter flows down the meter lead through the starter positive connection then through the carbon brush and then through the armature the coil and then through the other brush and hence down to the body (earth). So testing with a meter will show what looks like very low resistance. When the starter motor is removed and disassembled testing the components should show the armature having connection between adjacent segments that the brushes would rest on so that the current can flow through the armature via the brushes.

A known fault with the early Valeo starters is the permanent magnet pole piece separates from the body can due to bad glue and that means the pole piece floats about jamming the armature now and then. That can be repaired or replaced to fix that problem.

Having fully cleaned the starter and reassembled it with attention to reassembling it exactly as it was before you took it apart, put it back and connect it up.

So back to the first BMW test what is the battery voltage under starting load when you measure it with a good test meter?

Please report the voltage of the battery when it has been off charge say overnight and then when cranking the motor?
Regards,
K-BIKE

thanks for your reply. i removed the starter from the motor so I could inspect and clean it. I noticed that prior to it's removal, it was not turning. according to the haynes manual , the terminal must be completely insulated from the body, but when Ii tested my starter with a multimeter, there was continuity between the terminal and the body. I attached a wire from the positive terminal of the battery to the terminal and there was no movement. is that a problem? if there is continuity between the segments, i don't understand how the terminal can be insulated from the body. as soon as the brushes touches the segments, that would complete the circuit? clarification would be appreciated. ta

Hi Gabriel,
First a question do you have a Valeo starter with permanent magnet field coils or is it a Bosch with wired field coils? What Haynes is describing is a motor with field coils (Section 10 Starter Motor Overhaul and Paragraph 10 talks about the field coils). The Valeo is more common on the K I believe and the + terminal is insulated from the body until the motor is reassembled and the armature commutator segments provide the earth connection as I describe above. So which do you have the permanent magnet Valeo or the Bosch with field coils and what voltages are you getting as described in the BMW procedure above.
Regards,
K-BIKE

i have the nippon-denso? starter. there are four magnets attached to the maid body. perhaps the brushes need to be replaced. the starter appeared to be in good condition. how do i apply power to the starter to test it? the terminal is only insulated from the main body when it's not put back together.
regards gabriel

Hi Gabriel,
You apply + positive to the terminal and - negative to the body of the starter and it will spin like crazy when it is not cranking an engine over. There will be a big spark because it draws a lot of current and there is a significant torque reaction which tries to make the starter motor rotate so don't be surprised. Nippon Denso starters are OK.
Regards,
K-BIKE

thanks for your prompt reply. i made an attempt to power it up, but I only used a wire to connect power to the positive terminal. i dudnt earth the circuit. could that be the reason the starter did not turn? you mentioned a big spark. is this dangerous and are there any precautions i need to take to ensure I dont harm myself when i apply power to the starter motor.
regards gabriel. im not convinced the starter is faulty. the inside of the starter unit was in excellent condition. and there was no carbon deposits. the commutator appeared to be in good condition and there was no discoloration. perhaps the relay is faulty. I want to be certain the starter turns when i apply power before i conduct any further investigations.

To test: If you have the starter motor taken out, you can connect the motor directly to a good battery. The body shall be connected to the negative / earth of the battery.

Please hold it tightly, because it will "jerk" you when you apply power to it. If the motor is turning strongly. Then your starter motor is good and you can re-install it.

Good luck.

I used jumper leads to power the starter motor (positive terminal was attached to the starter motor terminal and negative terminal to the starter motor body). no response. any more ideas? should I take the unit to an auto electrician for a second opinion? im surprised its not working. the inside of the unit appeared to be in good condition, but I did notice there was continuity between the commutator segments and the armature core. apparently this is not a good sign? Help.......

Hi Gabriel,

I had the same experience with you. You need to take the starter motor out from the bike and test it independently as I explain previously.

If the motor does not run, then you can try to dismantled it. Please make sure you put sign at the bottom joint and top join of the motor. These will be the guide when you put the parts back.

The resistance (Ohm) of the moving part is very low. You must use digital AVO meter to get an accurate reading of the Ohm. Check also the magnet (attached in the inside of the cover body), make sure they are still in the correct position. Last, make sure the 2 brushes are still good.

After cleaning all the parts, you can re-assemble the motor. Starting by putting the top part to the round shell of motor with the armature inside it and last is the bottom part. Make sure the brushes are in the correct positions.

Then you can use jumper lead to test the motor.

Good luck.

Hi Gabriel,
If you took the starter motor out and connected the positive of a known good battery to the + terminal of the starter and the negative of the same battery to the body of the starter and it did not spin up then it is dead, kaput, stuffed etc., you need a replacement starter. If it spun at speed the starter is probably OK but as you said it didn't turn I believe it is dead, sorry.
Regards,
K-BIKE

hello. yesterday evening i decided to make another attempt to repair my bike. The starter motor was stored in a box. I made certain assumptions about the bike and the starter motor. when I disassembled the starter motor, i was surprised to find it in reasonably good condition. I reassembled the starter and attempted to apply power in an attempt to start it. I used jumper leads and this time I noticed that the starter motor turned. i was happy for a moment, but noticed that the motor did not turn with any great force and there was no spark. I was able to stop the starter motor using my hand . there was not any great torque. i was using a battery which was in average condition. I reattached the starter to the bike and switched on the ignition..no movement..using a multimter I noticed there was no power reaching trhe starter motor terminal. I noticed a loud muted buzzing noise originating from the electrical component box located under the fuel tank. i am convinced that there is a problem with the components in this box...one component in particular was making a buzzing noise and i could feel movement inside the component. i unplugged the approx ten pin connector and noticed there was a circuit boardd with components , including two mini relays and IC chips. I dont know how to test this component. can anyone advise me about the relays and how to test them. your assistance is appreciated. all the wires including earthh points were cleaned in the last twelve months.

Hi Gabriel,
One problem at a time you still have either a weak battery that you used for the test and or a faulty starter motor if you can stop it with your hand when powering it directly from a battery with I assume thick wires?

A starter motor should be strong enough to literally tear the flesh off if you tried to to stop it with your hand because it is designed to turn an engine over and that takes a lot of force.

So look at the circuit in the - Download - Electrical - Your K 100 Wont Start section that shows the sequence to follow and the circuit that the starter operates with.

BUT first you need a good battery and a good starter motor that turns the engine over powerfully. If you have a good battery and good starter then you should be able to turn over the engine quickly and then you can work through the my bike wont start sequence. Until you can get the starter spinning the engine over than you have zero chance of getting it going with the starter. Concentrate on getting a good battery and good starter motor first. Worry about other buzzing relays later that does not sound like the starter relay so that is all you are concerned with at the moment.

I suspect that once you have a good starter motor and battery many other problems will go away.

Regards,
K-BIKE

The advice above from K-BIKE is CORRECT.

I had the same problem. You test the starter motor with a good battery. After you make sure the starter motor is RUNNING well independently. Then you MUST make sure you have a good battery on the bike. Re-install the starter motor to the bike. I am sure you will get the bike runs.

A weak battery on the bike will cause buzzing noise and sometime shut off all electrical system.

I replace the battery on my bike to a 45AH Sealed Maintenance Free battery.

Good luck.

thank you for your quick response. I must admit that the battery I am currently using is in average condition. It has been allowed to run flat many times and I currently have it on a trickle charger. Don't know if this is relevant, but yesterday. i used a multimeter to test for voltage at the starter motor. I placed one probe on the terminal and the other to the starter body and pressed the starter button. I did not get a reading. I will repeat the test this afternoon, but if I tested it correctly, it means there is no voltage/power reaching the starter. I agree that a good battery is necessary, but I want to consider other options before spending big money purchasing a replacement battery. Is there any way I could test the components inside the electrical box. I used thick jumper leads to connect the battery to the starter. when I connected the final lead to the battery, there was a spark at the negative terminal. does that suggest that the battery is "strong". Once again, thanks for your prompt replies. your assistance is always appreciated. Summer is fast approaching and i miss my bike.

Pleeeaaaaseeee save your effort and time.

You MUST take out the starter motor from the bike and test it as explain previously. Use a good strong battery.

This is to make sure the motor is GOOD.

Then you know for sure the battery is weak or the starter motor is bad.

DO NOT TEST the motor in the bike.

A few days ago, i removed the starter from the bike and tested it using jumper leads and my battery. The starter was spinning but I could stop it quite easily using my hands. Ive let the battery run flat many times and I thought if I recharged it, I could reuse it? When i tested the battery using multimeter, I get a reading of approx 13 volts, I suppose it's not quite that simple? when I press the horn, i get a strained, muted sound...a clue that the battery is no good? but it doesnt explain why im not getting a voltage reading at the starter motor terminal? what do I need to consider when buying a replacement battery. i dont have any accessories attached to my bike, just the basics. thanks

Gabriel, there are batteries on Fleabay.

Mine was a 12v 18Ah golf cart battery (like you, I have no bells and whistles, not even ABS) so this battery should be fine.

It's an AGM (absorbed glass mat) type; it can be couriered to your
door as it is sealed and nothing can leak out...$75 or thereabouts.

hi everyone, especially those who responded to my query.
for the last few years I have experienced numerous problems with my bike....backfiring, rough idle,poor fuel consumption, eventually the bike refused to start. I had my suspicions but stubbornly refused to replace the battery. eventually i purchased a YUASA battery and I am happy to report that my bike is running like a switch watch!!!!! All my problems have disappeared and I never considered how vitally important a good battery is for an engine to run properly!!!!

Good news,
Regards,
K-BIKE

It is good that you have probably discovered the troubles with your bike being simply the battery. A good thing to remember is that in order to properly test a battery's true 'strength' what is needed is to fully charge the battery then attach it to a 'load tester' and see what the voltage drops to when the load is applied to it, after a specified period of time, usually ten seconds or less depending upon the battery's size/rating/amperage. If the volts drop to under say 9 volts and don't pop straight back up to above 12.5 or so then it's probably bought the farm. Repeated quick bursts of the load tester will confirm a weak battery.