1975 cb750f shifting issues...

[crk4130]

when i shift down into first gear from neutral i get a pretty loud crunchy noise like its having issues getting in gear.... the rest of my gears seem to be fine its just from neutral to first....  im a novice and this is my first bike so any help would be awesome... thanks guys

[Re-run]

How fast are you going when doing this? If it happens at any speed, I would guess the previous owner (PO)
probably bent a shift fork by downshifting from too high a rpm.

[crk4130]

it happens when im not even moving... now my clutch wont even engage at all... i can have my bike in any gear and it rolls like its in neutral.... do i need to rebuild the clutch? if so what do i need to purchase?

[Re-run]

It maybe possible there are broken springs or warped clutch plates. I would suggest draining your oil and pulling the clutch out. I say to drain the oil as if there is damage to the clutch, you do not want to leave that oil in.

[Cabreco]

Re-run wrote

How fast are you going when doing this? If it happens at any speed, I would guess the previous owner (PO)
probably bent a shift fork by downshifting from too high a rpm.

So coming to a stop sign & downshifting to 1st at 2500 rpm with the clutch pulled in on this bike is a no no?
I notice that when downshifting I get this crunch on each gear down progressively louder (first being the loudest). No issues going into gear, upshifting or when stopped from neutral to 1st.

I don't recall my CB 500 being this loud - then again that was almost 30 years ago!

[Re-run]

A lot of the shifting noise comes from the oil used. Regular 10-40s are ok but I prefer diesel oils as shifting is usually better.
I think the sounds gets louder though with the lower number of teeth but I dont know.

[Cabreco]

Re-run wrote

A lot of the shifting noise comes from the oil used. Regular 10-40s are ok but I prefer diesel oils as shifting is usually better.
I think the sounds gets louder though with the lower number of teeth but I dont know.

The oil in this was changed in March by th PO & it is still nice & gold but I have no idea what he used.
I'll be doing an oil change next week & use Diesel Engine oil. He may have used the right stuff but since I don't know I think I'll change it & the filter. Cheap enough price to pay for piece of mind.

[Re-run]

I use rotella synthetic 5-40 but the rotella t 15-40 worked pretty good too.