Motorcycle Repair: 1981 CB750C primary shaft, gearing ratios, clutch basket

Question
On the end of the primary shaft there is a split gear that engages the clutch basket.  What is the purpose of having the main gear with 24 teeth and the thin sub gear with only 23 teeth?  What kind of problems can it cause if the subgear doesn't work like it is suppose to?  I have a slow, rythmic growling noise that seems to come from the tranny, yet in having dissassembled the crankcase, can find nothing wrong with any gears or bearings.

Answer
Hi Cliff,

Do you have the factory service manual? If not, I recommend the manual for such repairs. Follow the manual's procedures for inspecting and measurings service limits on bearings and transmission parts.

Helical cut gears make a specific sound. I would need to hear the sounds you've described to offer an accurate diagnostic opinion.

At this point, measure all parts and try to find the source of the noise.

Reference your gearing questions: Each gear has a function to make work of the driven gear: such as a starter motor or oil pump, etc... Smaller gear=less load. Gearing ratios (points or teeth) are determined by needs.

If the parts were defective, a list of symptoms and problems would be likely to follow.

Respectfully,
Mark Shively