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 your subject.
1970 Triumph Bonneville 650 Heads
Q: I own a 1970 Triumph Bonneville 650 with the wrong head. The head on my bike right now is a 1971. Since it is very difficult to find a good 1970 head, do you think I can use a 1966-1968 head? What are the differences? - Lorenzo Tripaldi/via email
A: I didn’t know the answer to this question, so I enlisted the help of a Triumph aficionado I know. Eric’s built a few Triumph engines from parts, so he’s been in your shoes. This is what he had to say: “All 650 unit engines had nine-bolt heads up until 1972, so there shouldn’t be a problem as long as the jugs have nine holes. They did change the threads to unified threads in 1969.” That shouldn’t matter as long as you use the head bolts you already have. MC