Topic: 1974 cb750k4 clutch/transmission noise when decelerating to stop

[Hoffsquig]

Hey all, just hoping for some advice on where to start first.  Just finished this build, and took it out today.  It sat in various positions for 4 years, but i had been able to test ride once b4, and didnt notice any issues.

When I first started the ride, it was stalling as soon as I shifted into first.  That happened about 4 times, but eventually got past it.  Just assumed the plates were sticky from sitting for a couple months. 

Took a ride and things were good until i was almost home. 

- clutch was slipping?  In 3rd and 4th.  I assume thats what it is...felt like it was in gear, but rpms would skyrocket is until i shifted again. 

-  when coming to a stop, almost completely stopped, with clutch lever pulled in, in 1st gear, makes an awful chunky, clunky noise that seems to slow as the bike slows.  Sounds like its coming from the trans area of the case, and causes some slight jerking/knocking and vibration felt all the way up to the seat.  Feels similar to hitting a gear a little wrong and bouncing off repeatedly.  But im all the way in first, amd the clutch is disengaged.  After the noise, amd completely stopped, it takes off again fine like the gears are perfectly normal.

Any thoughts on what this could be?  The clunky noise/feel when almost stopped is significant and concerning.  Did I mess up some plates running them dry or something?  Just a bad adjustment after everything got really warmed up the first time? 

Last oil change was just before this ride, with 20w50 valvoline motorcycle oil.  No other history to compare it to since i rode it home 4 years ago when i bought it.

[Hoffsquig]

I should add, I did the clutch rebuild along with the engine rebuild.  Amd im far from even average at it.  Just followed the manuals.  But if i remember correctly, i bought new plates, and cant recall if i lubed them or soaked them or anything before install.  I can assume I did...lets say 80/20.

[bryanj]

Unfortunately sounds like something inside the gearbox has failed

[Hoffsquig]

Not that im doubting you at all Bryan, but is there any good explanation that it would only make the sound/feel at say 2-3 mph and decelerating?  It doesnt happen in the same gear when accelerating or above that speed.  I'll ride it slowly around a parking lot tonight to see if I can get any more info.

[Hoffsquig]

I did notice that it pushes quite easily in first gear.  Which I didnt think was supposed to be the case.  Short of pulling the engine and splitting the cases, maybe ill check the shifter assembly.  It happened sometime during that ride, and was not a gradual failure.  Performed flawlessly for 45 minutes, through all gears until the last mile

[69cb750]

- clutch was slipping?  In 3rd and 4th.  I assume thats what it is...felt like it was in gear, but rpms would skyrocket is until i shifted again. 

If engine gains speed faster then bike in 3rd and 4th the clutch is slipping.
Check adjustment under chrome clutch cover.

[bryanj]

The way i read it was you had no drive in 3rd and 4thwhich means something broke

[Hoffsquig]

Bryan, it was good in 3rd and 4th other than the slip a few times during that last mile.  When id shift up or down, it would catch again. That started in the same mile as the 1st gear clunky noise issue, i just didnt notice the first gear problem described until i got into town and hit the first stop sign.

Ill check the clutch adjustment again.  Ive done it a couple times already, and thought i had it right.  But its an aftermarket handle/perch/cable and gave me some difficulty at that end.