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Tech Corner

Technical Q and A for classic motorcycle maintenance and repair.

BMW K100RS Wiring

Motorcycle Classics tech expert Keith Fellenstein

Editor’s note: If you’re having trouble with that old Suzuki, BSA or BMW, Keith Fellenstein is your guy. From motorcycle tuning tips to detailed motorcycle engine repair, he can draw from a wealth of experience to help guide you to success. Send questions to: Keith’s Garage, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

BMW Wiring

Q: Can you please help me with the correct connection of the wires on the ignition coils of my BMW K100RS? — Corrie/via email

A: The brown wire is common to both coils, as is the green/yellow wire. The blue/black wire goes to the front coil while the black/red wire goes to the rear coil. The front coil is for cylinders 1 and 4. Looking at it from the bottom, the blue/black wire is at the top, brown in the middle and green/yellow at the bottom. On the rear coil (cylinders 2 and 3) the top is black/red, the middle brown, and the bottom green/yellow. MC