K100 Starter removal/cleaning

I have read a few threads and the ibmwr tech pages on removing/cleaning the starter to (hopefully) solve the poor shed load relay ground issue and intermittent starts. Questions:

1. Do i need to completely disassemble the commutator/brush holder plate?
2. What do I use to clean the internal parts? I have heard both brake cleaner and carb/choke cleaner, but then the manual warns against them as they will eat the insulation on the commutator wiring--so just use contact cleaner spray in that part? Can I spray that intact as a unit?

Thanks!

Not sure what the experts say but I used electrical contact cleaner and compressed air. I did disassemble mine to gain access to the brushes and comutator (spelling) ring to clean it also. If my feeble memory serves me I used very fine emery paper to polish it and plastic door shim to clean the grooves. Took some time but has worked fine since.

Roy

mgordon said:

I have read a few threads and the ibmwr tech pages on removing/cleaning the starter to (hopefully) solve the poor shed load relay ground issue and intermittent starts. Questions:

1. Do i need to completely disassemble the commutator/brush holder plate?
2. What do I use to clean the internal parts? I have heard both brake cleaner and carb/choke cleaner, but then the manual warns against them as they will eat the insulation on the commutator wiring--so just use contact cleaner spray in that part? Can I spray that intact as a unit?

Thanks!

Click to expand...

Hi.. (well.. dunno your name - hint!)..

1. No. Cleaning it with some solvent and a Q-Tip should work just fine. You do want to check the brush length. One of the aftermarket manuals has that spec (I no longer have the manuals - sold them when I sold my K..) If the brushes are too short they'll tend to hang in the brush holder and the starter won't work. New ones aren't expensive, but they must be soldered in - so if that isn't a skill you picked up along the way, you may want to look for someone who knows how to solder to help. FWIW - the starter is made by Nippon-Densa, and almost identical ones are used on several Japanese bikes. Parts may be cheaper sourced from other then BMW sources.

2. Contact cleaner, brake cleaner, carb cleaner, all are pretty much the same thing now. If you have it - contact cleaner will work just fine, if you don't and have one of the others - have to it.. just don't leave it soaking on the parts.. Most of these solvents evaporate rather quickly so it isn't a concern. Use them OUTSIDE with good ventilation!

As Roy pointed out - won't hurt to clean the commutator with some super fine emory paper (1000 grit would be a good thing to use..) Just make sure you clean it really well when done so no grit is left behind.

DO MARK THE ENDCAPS - before dissasembling. I scribe 1 line across the endcap/body joint on one end, and 2 lines (close together) on the other end. This will help in getting them back in the right place.

Good luck!

Mission Accomplished

Hi, this is Mike...

Thank you for your help. Getting the starter out and cleaning it was a fairly straightforward job. I had to use an impact driver to get one of the starter casing screws off, but i got it with some coercion.

Definitely some dust in the commutator/plate assembly endcap, and a good amount of grime washed off the casing/magnets/stator/rotor.

Bike fired up and signals all work normal!!

Brushes seem to be ok. Unfortunately, I didn't refer back to my Clymer and measured them for height not depth>>DOH! But they look to have good length on them still.

Thanks!

BMW actually sells a starter rebuild kit with new brushes so this is now a 15 minute job..

Mark caps, scews out, clean, out parts out, new parts in, grease, caps on.