K100 motor just died

[Dynadavid]

Hi all,
This is my first post on the forum.
I've had a 1987 K100 for 4 years, it has 38,000 miles on it, I use it regularly for my 20 mile commute, do the oils and filter myself and until yesterday it always started on the button and ran perfectly.
Yesterday, I was in the centre of Dublin when the motor just died with no warning, there was no misfiring or rough running and no nasty mechanical noises- it just coasted to a halt at the side of the road. (Which let me tell you, in Dublin at 6pm is no laughing matter)
The electrics all seemed to be working- front and rear lights on, warning panel lights lit up etc. When I pressed the starter button the fuel pump started up but the starter motor was silent ie didn't even try to turn the engine over. I couldn't hear the solenoid clicking, but as it's under the tank, maybe it was being muffled a bit.
I now have the bike at home and just don't know where to start looking- can anybody help with a check-list of possible faults please?
Thanks,
Dave (Dublin, Ireland)

 

[JohnHall]

The first order of business is to check all of your fuses. Then if you don't have the schematics somebody here could maybe do some tracing for you.

 

[Gil]

Could it be possible to remove the fuel hose that leads to the injectors and see if fuel is getting pumped? I would also check the ignition switch. Keep in mind that a bad switch may turn on the electric panel, lights and accesories but fail to make the last point of connection for the engine poser. Also check the thumb cut off switch on the right. It could be as simple as that switch failing.
Best of luck.

Gil

 

[beemer01]

Hmm.

OK, the first thing I would do, if you haven't already, is try and bump start the bike. If it won't start, I'd first check the fuel filter.

Mine died the same way on the vast prairies of the Great Plains here in the States. The fuel filter was clogged because the fuel damper had essentially melted into tar. If the filter is clogged, I suggest draining the gasoline and checking the condition of the damper and initial screen at the base of the fuel pump.

The no starter motor thing I'll let someone else opine on the starter motor - good ideas have already been advanced. I'd also put a voltmeter on it and see if it's getting any juice when you hit the starter switch.

 

[cayuse60]

Hi Dave,

http://www.bmbikes.co.uk/forumpage.htm

You will be able to contact some K bike types right in Dublin by logging on the link.

I'm in my office at work and do not have the wire diagram for the start ignition circuit. Hard to check if you have a spark without the starter operational.

I'll check the start/run circuit when I get home.

good luck----Tim

http://www.bmw-club.org.uk/~irish/

this link will get you directly to the Ireland branch.

 

[richo2006]

My bike ('85 K100) did the same thing. I traced the problem and it turned out to be the ignition module. I didn't have spark. I forget how I traced the problem to the ignition module.


Richard Flood
Commerce Michigan

 

[HFbmw]

k bike died

Aha!
I just had that problem on thursday! Well maybe its the same problem!
No lights? no tail lights no brakes? Bike ran fine then died?

Pull the starter. Clean the commutator with an ink eraser. (copper end of armature) put the starter back together after cleaning out all traces of carbon. Make sure the label on the outside of the motor is closer to the gear protruding out of the starter...

Now try it. It might start! Grounding for the electronics runs through the starter.
Brushes are part of the grounding system on the bike..

I had to replace the brushes on my bike today. I had read here and other places that its wise to carry a pair of brushes... Sooo I replaced mine and what a difference! Headlight is lots brighter!

My K100 has over 134,000 miles under its oil pan... You might not need to replace the brushes just yet...

check out the website www.ibmwr.org too. Lots of good info!

keep us posted!

tim lindstrom
91k100lt

 

[HFbmw]

k bike died part II

I reread your message. stating you had lights and the rest...

Proubly still the grounding. Lights don't take much of a load from the battery.
fuel pump and starter motor takes more.

Last fall when coming home from Texas I stopped for my last fuel in a small town south of the minneapolis metro. I had been riding all day from oklahoma city. (650 miles) After shutting the fuel cap down I hit the starter. Nothing!

You all know that sinking feeling! I had the bike sitting toward the conveniance store and could see the headlight shining... hit the starter again... nothin...
So I put it in 2nd gear and rocked the bike... Fired right off.

rode the rest of the way home watching the lights flicker and finally go out. Praying for a safe ride as the sun had set.

next day I pulled the starter and cleaned the commutator and the bike awoke from its lightless slumber. Smiles abounded as I rode off into the sunrise... eh

Anyways. check the grounding of the machine which is thru the starter.

tim lindstrom
minneapolis, mn
91k bike