Shaking and knocking with clutch engaged

Hi, I’m fairly new to riding bikes, as well as working on them, but I have built multiple cars and worked in the automotive industry for a couple of years. I have a 1980 Yamaha XJ650 Maxim, that I received in a non running condition. Was a bobber project for a guy that I returned to stock. Rebuilt carbs, pieced together intake, and some other misc electrical stuff. I also messed with the clutch some to try to get rid of that pop when put into first, not realizing it’s fairly normal. Took it for its first ride around the court and noticed some slipping, so I put it back to what seemed like where it was. I did not notice any shaking similar to what was seen on the center stand, I think I would have felt it. I put it on its center stand and ran it through the gears and noticed it was shaking and clunking a bit in fourth. When I pulled the clutch it went away. I then found it did it through all gears, and only stopped when the clutch was pulled. I initially thought it would be u joint or shaft related but I don’t think so, as the wheel continues spinning and it stops making the noise and shaking. Has anyone with experience seen this before?

I will also add that I searched and couldn’t find anything related. But, on a somewhat similar thread (it was determined to be the middle gear popping when put in gear) someone mentioned clutch shudder. Is it possible this is it?

 

what did you do to the clutch when you " I also messed with the clutch some "?

what rpm was the test done under?

 

I adjusted the clutch cable at the case, not the lever. I adjusted it up some initially, then it started slipping. Then I adjusted it back down to what seemed like where it was. The rpms were up to around 3k in each gear.

 

This sounds like a dangerous thing to do.
I would expect a bit of jumping and shaking about to happen

 

Am I probably just stupid and was hearing the center stand bounce about? And I probably shouldn’t do anymore as it’s a risk for me and my house?

edit: I’ve done some more research and digging and I had not thought about the idea of possible damage to the u joint from running the bike in gear with the rear suspension fully extended.

 

You won’t damage the u-joint by running on the center stand.
If there is something wrong with the clutch, or your u-joint is already seized, or you had previously pulled the rear and the shaft isn’t back in right—- those could cause damage.

sounds like a clutch issue though to me

 

Know this is an old thread at this point but just thought I’d respond with what it was. Took it back out last week and the clutch slipped a little when cold. Tightened up, done. Rides totally perfect now.