Wont Start - Starter? Load Shed Relay? Alternator?

[jamato]

I have been experiencing odd symptoms from my 1987 K75s lately the past 3 days.  Many of which I've read in the forum recently however I have an added element.

- lights stay on after bike is off and key out.  I have to jiggle the load shed relay to resolve this.

- bike won't start with ignition;  No turning over at all, just a click from either the load shed relay or the ignition relay is heard.  I have to bump start it. (much prefer to just push a button)

-sometimes while riding after a bump start, headlight is off and signals do not work.  10 minutes into the ride, all work fine.

My question.  Is this the starter itself, the connection to the starter or the load shed relay causing these issues?

Any input is appreciated.

Thanks
Joe

[K75RT Keith]

More than likely you need to clean the starter.  It is an easy job that you can do yourself.   See  www.ibmwr.org/ktech and scroll down to STARTER.  Cleaning is simple.  Just remember to mark the case as reversing it will make your starter run backwards.

If the starter contacts are dirty and/or the brushes are worn down you can get a dead spot which requires bump starting to get past the affected area.   

Load Shed Relay has NO AFFECT on starting.  It only bypasses the load created by the lighting circuits and other circuits that are not related to starting.  Lifting the tank and jiggling it sounds like it's a candidate for replacement. it would also explain your light issues.   

If it were me, I'd: Clean the starter and possibly replace the brushes.  Clean All grounding points under the tank and transmission (main from battery.  Clean the starter connections.  Charge the battery and replace the load shed relay with a new one.

[TimTyler]

Sounds to me like a dead battery and a stuck starter relay.

[lmiklosy]

     K75RT Keith is exactly right, in the starter motor the commutator has stopped on a flat spot that won't pass electric current. Here' s a very quick fix that'll get you goin':1. Sitting on the bike, key in the OFF position, rock the bike and put into 5th gear.
2. Pull the clutch and roll the bike BACKWARD a foot or a little more.
3. With the bike still moving dump the clutch, you should hear the starter engage and spin backward.4. Put the bike in Neutral, choke, key ON and hit the starter.

That worked for me and the bike started immediately. The starter has a freewheel clutch, when rolling backward the clutch engages and rotates the commutator off the dead zone and the starter will work again.  Next, do as Keith recommended and clean the starter, that is dismantle the starter to clean the gunk out of it. You'll be good for many more miles.   
 

[Steviescumbag]

Hey friends. I am also getting starting issues with my 92 k75 rt.
When I turn the ignition on all lights work, headlight, blinkers, etc. as soon as I pull in the clutch and press the starter the headlight cuts out and there’s buzzing coming from under the tank. When I let go of starter the headlight comes back on. Could this be grounding issue or starter relay? Let me know what you think and what’s the best solution.

Thank you.
Tried posting video but doesn’t load

[rbm]

Stevie, sounds like a depleted battery.  The lights going out and returning is normal. Thats the LSR working.  The buzzing is the starter not being able to engage.   Measure the battery terminal voltage before and during starting and report back.

[Steviescumbag]

Okay thanks for the advice. How do I do this, what am I looking for?

[Laitch]

How do I do this, what am I looking for?

This video explains it. Keep in mind, the video does "not get right into it." You must listen to intro music first.  Also, as the presenter indicates, you could die doing this.  If you aren't ready to shuffle off this mortal coil yet, remove the battery and take it to an auto parts store like NAPA, Pep Boys, AutoZone or another large auto parts retailer. They'll usually load test it for free.

[rbm]

Use  your voltmeter in DCV mode to measure the battery voltage at the terminals.  Positive lead on battery positive terminal and negative lead on negative terminal
mesure the voltage with ignition off, ignition on and starter cranking while pressing the start button. You might need help because you have to use both hands to start the bike.

On my bike with a good battery I read. 12.99V with the ignition off, 11.89V with the ignition on and 10.46V while cranking the engine.

If you see the voltage dip below 10V while cranking, then your battery may be too weak to supply the current needed to turn over the engine.

[Steviescumbag]

Sweet. Thank you for the help!
Will try and get back soon.

Also, I might as well ask. What battery do you use? I also wonder how some people that converted their bikes to naked bikes use tiny batteries, which ones are those?

[Steviescumbag]

Update:

I just went ahead and purchased a new battery anyways.

Readings are all similar to what you said above, all though when I crank the engine it reads above 12. (12.6)

Still doesn’t turn, buzz coming from under the tank where all the relays are.

What can I try now?

[rbm]

OK, so several things are pointing to the starter relay as the culprit..(1) your battery terminal voltage remained pretty high meaning no appreciable current was being drawn from it.  (2) the starter didn't turn over confirming (1).  (3) the buzzing sound indicates a bad relay that won't engage.

So, make a test or a series of tests. Don't make any more parts replacements until you've diagnosed the problem.  You'll be introducing more variables in the problem and never get to resolution.

test 1:  Is the starter relay crap?
1. open the relay box and remove the white plastic coil plug from starter relay
2. use an ohmmeter to measure resistance between the contact tabs.  You should read about 60-80Ohms.  If it is near zero, shorted coil. If it is open circuit, broken coil. Bad relay in either case.
3. Above resistance test passes, then remove the relay an open it up.  Apply 12V directly to the coil using jumper wires to your battery.  Observe the action.  Does the coil pick?  Do the contacts close?  Does it buzz and do nothing?  Make a determination whether the relay can be fixed or to buy a new one
4. If it picks and the contacts appear to close, then use your ohmmeter to measure whether the contacts are actually closing and making good contact.  The reading should be zero ohms or near to it (0.1 Ohms).  If not, the relay is bad.  replace it.

test 2:  Is it the starter?
5. to finally verify your starter motor is not bad, take the two red wires that were connected to the relay in the fuse box and press them together to make electrical contact.  NOTE: BE CERTAIN THE BIKE IS IN NEUTRAL AND ON THE CENTRE STAND.  Don't do this in gear.  If the starter turns further proof the starter relay is bad.

[frankenduck]

OK, so several things are pointing to the starter relay as the culprit..(1) your battery terminal voltage remained pretty high meaning no appreciable current was being drawn from it.  (2) the starter didn't turn over confirming (1).  (3) the buzzing sound indicates a bad relay that won't engage.

So, make a test or a series of tests.

test 1:  Is the starter relay crap?
1. open the relay box and remove the white plastic coil plug from starter relay
2. use an ohmmeter to measure resistance between the contact tabs.  You should read about 60-80Ohms.  If it is near zero, shorted coil. If it is open circuit, broken coil. Bad relay in either case.
3. Above resistance test passes, then remove the relay an open it up.  Apply 12V directly to the coil using jumper wires to your battery.  Observe the action.  Does the coil pick?  Do the contacts close?  Does it buzz and do nothing?  Make a determination whether the relay can be fixed or to buy a new one
4. If it picks and the contacts appear to close, then use your ohmmeter to measure whether the contacts are actually closing and making good contact.  The reading should be zero ohms or near to it (0.1 Ohms).  If not, the relay is bad.  replace it.
5. to finally verify your starter motor is not bad, take the two red wires that were connected to the relay in the fuse box and press them together to make electrical contact.  NOTE: BE CERTAIN THE BIKE IS IN NEUTRAL AND ON THE CENTRE STAND.  Don't do this in gear.  If the starter turns further proof the starter relay is bad.

I'd just do #5 first by just putting a screwdriver across the two bolted terminals on top of the starter relay (in NEUTRAL as rbm suggests.)

One thing to note is that the lead that goes to the rear starter relay terminal is always "hot" and connected directly to the battery's + terminal.(Unfused.)

If you're going to remove/replace the starter relay it's a good idea to disconnect the battery ground cable on the transmission next to the shift lever in order to avoid any accidental shorts with that hot starter relay wire.

[Steviescumbag]

Love it. Thanks. Will try all of the above and report back. You explained it like you were explaining to a 3rd grader and I appreciate that loll.

Side note: I did not mention this but I have taken out the starter, opened it up, it was full of debris but I cleaned it well, looks like new, and put it back. But still same thing, so yes maybe a starter relay issue.

In worst case scenario. Where’s a good place to guy a starter relay for K75 rt.

[Steviescumbag]

Also, I have tried the screw driver trick between the 2 bolts. Some sparks, and I hear the relay click but nothing happens.

[rbm]

In worst case scenario. Where’s a good place to guy a starter relay for K75 rt.

See this BMWMOA thread for discussion of equivalent part numbers from Bosch and Tyco for the standard OEM Bosch starter relay.  Use your Google-fu to find cheap relays online.

[frankenduck]

If the starter does not turn when you do the screwdriver short then you have starter motor issues IMO.

You can get used starters dirt cheap on eBay. Here's one for $14.20 shipped.
https://www.ebay.com/itm/255650861944

(I am not affiliated with the seller.)

[Steviescumbag]

Mine looks in better condition than that one 😂 but thank you!

[frankenduck]

Mine looks in better condition than that one 😂 but thank you!

The good thing about Ebay these days is that you can return anything for free. They ALWAYS side with the buyer. (Shitty for sellers but great for buyers.)

And don't judge a starter by its cover. There is not a direct correlation between external appearance and internal functionality. I've seen low mile starters that looked like crap and high mile starters that were very clean from always garaged bikes.

I wouldn't hesitate to try out that starter but that's just cheapo ole me who lives by the adage that the cheapest part on a BMW is the owner.

[Steviescumbag]

I know I’m just busting your chops. I’ll give that a try. My starter did look in great shape on the inside though. I would i be looking for to see if it’s faulty?