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Tech Corner

Technical Q and A for classic motorcycle maintenance and repair.

1965 T100 Triumph Smoking Cylinder

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, Motorcycle Classics, 1503 SW 42nd St., Topeka, KS 66609, or send an e-mail with “Keith’s Garage” as the subject.

Lots of smoke

Q: I am 63 years old. I have had my own little shop under my house for about 43 years. I have fixed just about every brand in those years. I bought a 1965 T100 Triumph 500 from a friend of mine about seven years ago. When I had a little extra cash I would throw it in the bike. I finally got it running. When I fired it up the left side cylinder smoked very badly. I rebuilt the whole engine. I had the head done by E & V Engines, new valve guides and valves, new pistons and rings at 0.20 over. I cannot figure out why it is smoking only on one side. I even put another set of new rings in it and it’s still smoking. I don’t know everything, but I think I put the engine together right. I hope you can help me. Larry Petras/Ohio

A: After talking with Larry, it seems as though he’s done about all he can to eliminate the common causes of smoking. All I could suggest was that maybe the left cylinder was not concentric and that was keeping the oil scraper from cleaning off the excess oil. I suggested he back off the valve adjusters so that they wouldn’t open, and then do a leakdown test at TDC, mid-stroke, and BDC to see if there was any change in the amount of air getting past the rings. Another possibility would be a crack in the head letting oil leak down from the overhead valves. Do any of our readers have other suggestions as to what the problem may be? MC