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: While riding my 1971 Honda CL450 one day, a clattering noise came from the engine. When I returned home I left the bike idling in the driveway and soon discovered a pool of oil. One muffler was filled with oil and oil was dripping out through the bottom vent hole. What happened inside the engine that would cause this? — Wes Martin/via email
A: Unfortunately, any number of things could have gone wrong. Did the bike run any differently after you heard the clattering noise? Having one muffler fill with oil makes me wonder if an exhaust valve guide has come loose and is draining oil from the head directly into the exhaust. I’m afraid you’ll have to pull the top off the engine and do more research. MC