1967 Triumph Bonneville Carburetor Issues


| 11/23/2016 12:00:00 AM


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.

Carburetor issues

Q: I have a 1967 Triumph Bonneville with 18,000 miles on it. It recently started running with a rough exhaust note once it was warm. After sitting all winter it started with one kick, but from then on it ran very rough. The left cylinder exhaust ran hot on start. The pipe and exhaust were hot while the right side was cool. I thought maybe I had a tight exhaust valve, so I adjusted it. It was better, but still not right, so I readjusted it, and the left cylinder went back to running hot. It still starts on the first kick. I have also noticed that the carburetor ticklers take forever to flow, where in the past they filled more quickly. – Peter/via email

A:  When you say the right pipe was cool it sounds like maybe the right cylinder wasn’t firing, or did you mean that in comparison to the left it was cooler? Assuming you meant the latter, and knowing that it sat all winter, I’d suspect a restricted/clogged jet on the left carburetor leading to a lean condition for that cylinder. Just to be sure of the state of the fuel system, I’d pull the carburetors and clean them both. Since you mention difficulty in getting the ticklers to work well, double check the float heights. They shouldn’t change on their own; they are difficult enough to change on purpose unless you are using the new StayUp floats. Another possibility if the bike is still on points would be timing differences, with the left cylinder running with the timing retarded in relation to the right cylinder, but since you said it ran well enough when parked I’d check the fuel delivery system first.



tomd7735
12/1/2016 9:45:32 AM

Just a note; On my '67 Bonny the pilot jet is not behind the idle mixture screw, but is screwed up into the bottom of the float bowl flange. Visible when the bowl is removed and the carb held upside down. One needs a .016" or #78 drill bit and solvent to clean this and the passage ways.


lanceditty01
12/1/2016 8:38:40 AM

Amal carbs are testy and need to be cleaned no les than once a year. Its not to difficult on the concentric type. The old monobloc will test your skills




The sound and the fury: celebrate the machines that changed the world!

Motorcycle Classics JulAug 16Motorcycle Classics is America's premier magazine for collectors and enthusiasts, dreamers and restorers, newcomers and life long motorheads who love the sound and the beauty of classic bikes. Every issue  delivers exciting and evocative articles and photographs of the most brilliant, unusual and popular motorcycles ever made!

Save Even More Money with our RALLY-RATE plan!

Pay now with a credit card and take advantage of our RALLY-RATE automatic renewal savings plan. You save an additional $4.95 and get 6 issues of Motorcycle Classics for only $24.95 (USA only).

Or, Bill Me Later and I'll pay just $29.95 for a one year subscription!




Facebook Pinterest Instagram YouTube Twitter

Free Product Information Classifieds