Okay, so I finally got my hands on a 1991 BMW K100. I’ve always loved these “flying brick” bikes, and I was stoked to start this project.

First things first, I assessed the overall condition. It was running, but rough. Lots of cosmetic issues, some rust spots, and it definitely needed a good once-over mechanically.
Getting Started
- I started by giving it a thorough wash. Years of grime and dust had to go.
- Next, I tackled the rust. Some steel wool and rust remover did the trick for the smaller spots.
- I drained all the fluids – oil, coolant, brake fluid. They were all pretty nasty.
Diving Deeper
Then came the more involved stuff. I pulled the fuel tank and cleaned it out – surprisingly, there wasn’t too much gunk inside. The fuel injectors were a little clogged, so I soaked them in cleaner and carefully scrubbed them.
The brakes were spongy, so I rebuilt the calipers and master cylinder. New pads, new lines, the whole shebang. Safety first, right?
- Checked valve clearences.
- Changed timing chain tensioner.
Putting It Back Together
With the major mechanical stuff sorted, I moved on to the cosmetics. I sanded down the fairing and side panels, prepping them for a fresh coat of paint. I went with a classic BMW alpine white – can’t go wrong with that.
Finally, I reassembled everything, replaced some worn-out rubber bits, and polished up the chrome. It was a long process, but seeing the finished product made it all worthwhile.

Now, she runs like a dream and looks pretty darn good, too. This K100 is ready to hit the road again!