Technical Q and A for classic motorcycle maintenance and repair.
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.
Q: I have a 1980 Honda CX500C. It starts easily and runs great until it gets warm. Once warm, it loses spark on one cylinder. Any suggestions as to what is wrong with my bike? — Mitchell Smith/via email
A: It is likely you have a bad coil that is opening up when it gets warm. You could try switching the coils from one side to the other and see if the problem follows the coil. If it does, you can bet the problem is with the coil. MC