Motorcycle Repair/CB77 downshift problem
On occasions my 1965 CB77 will lock in 4th gear when I attempt to downshift to 3rd. I must stop and rock the bike to complete the shift. This does not happen with any other gear. In my attempt to fix this should I concentrate my efforts with the gear shift arm and guide mechanism behind the clutch or the gear shift drum and forks inside the transmission? Or, is there another solution.
I sought your advice once before and found that you were spot on. I appreciate you willingness to help me and others with you time and expert advice. Thank you.
This sounds like an internal transmission problem. Depending upon the mileage on the engine/transmission and the way it was treated in the past, most likely it needs to be removed and inspected for wear/damage to the shift forks/shift drum slot or shift selector peg and gear dogs associated with this gear set.
There are offset gear cotters which are usually required to improve shift function for the middle gears. The low gear bushing is often worn causing both engagement problems and in worst cases, the kickstarter function as well.
I think splitting the cases is going to be required in any event. If the end of the shift drum is damaged, you have to disassemble the bottom end anyway. Considering that it is only doing this behavior in top gear, it pretty much rules out the rest of the shift selector components. You can pull the clutch cover, primary gears/clutch basket and then have a close look at the selector components before pulling the motor, but I doubt that the fix is going to be easy and quick. The shift drum and selector parts are universal in almost all 250-305 motors. The transmissions are shared with the CL72-77 Scramblers, as well, so it is often easier to buy a whole transmission from eBay then selected NOS parts, which can run over $100 each.
I have restoration guide CD/Downloads available for the Super Hawks, if needed. Contact me through my website. I also have low gear bushings and offset cotters in limited supply.