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 thoroughly enjoy reading your column and sometimes find myself amazed at the questions you respond to. Wow, I never would have thought motorcycle problems could get so convoluted! Anyway, my problem is perhaps simpler. I’m currently putting new crank seals in a 1973 Kawasaki F7-B 175. It is a great bike that I hope to have in restored shape by winter’s end. I didn’t have any problems installing the seals, as I have done that before. I have several Kawasaki service manuals and I can’t find the correct torque for the primary drive gear nut or the clutch hub nut listed anywhere. Can you help? — Chuck Floyd/Whitehall, Mich.
A: I had barely started digging through my manuals when I received a follow-up email from Chuck. A friend of his had found the torque specs in an old Chilton’s Master Service Manual. Since these specs apparently are missing from the other common shop manuals, I thought it would be useful to share them here. He says the primary drive gear nut should be torqued to 51-54ft/lb and the clutch hub nut should be 58-80ft/lb. That last spec seems to cover too wide a range of torque values; I’d be inclined to use the lower end of the range and not try for the top. Both of those nuts have tab washers to help lock them in place, so there shouldn’t be any problem with them unwinding. A little blue Loctite couldn’t hurt, though. MC