help, Clutch suddenly stopped working

[Guest]

So a little backstory and info to start off. Its a 1977 GS750 with 19300 miles on it. The week before last i took it out for a pretty hard ride and came home, no issues or anything weird. I park it for about an hour and come out to do an oil change. Dumb old me bought the wrong oil but it was too late. I fired the bike up to pull it into the garage and i have zero clutch. There is pressure at the lever and feels normal. I flushed it, filled with cheap valvoline moto oil, drained that to take out whatever was left. Opened the clutch cover and wiped down all the plates. They are hard as a rock. (Unkown clutch pack age) Then refilled with reputable rotella t4.... fired it up and still nothing.

As i have the bike running i can shift into any gear and let the clutch out fully. The bike does not stall or try to move like normal. On the center stand and the rear wheel raised there is no driveline friction to let the wheel spin on its own. I can feel the shift forks "clunk" into there spot and go into gear so i dont thinks its the transmission. I have a feeling between the rock hard fibers and the oil mishap, i finally killed them.

I ordered new EBC fiber plates (steels looked in good shape. No uneven wear, no hotspots) new Versah HD springs, and a new clutch cable since it was due. When that arrives i will soak them in more rotella t4 for 24hrs. Readjust the actuator, and set the new cable slack.

Is there anything I'm overlooking since im still newer to bikes. I dont think its a transmission issue but im unsure. I feel like just a clutch issue but I'd like to hear what you experts have to say on the matter. Am i on the right track or would it seem i have an underlying problem here that i may be overlooking?

[Big T]

You should probably check the actuator in the left side case
Clutches don't suddenly fail
You'll probably regret those HD clutch springs

[Guest]

That is what was throwing me off. The sudden fail of how it happened. I will do a full readjustment on it when it all comes in. Are the HD's really that bad at the lever? Think i should just pick up some standards instead?

[Rob S.]

Think i should just pick up some standards instead?

That what everybody around here says - stick with stock clutch springs.

[Guest]

Good to know. I'll just have to get some standards coming then. I'll have these in the shed for backups i guess. I just hope this takes care off whatever issue its having... it cant be broken when you just replace it all 😉

[Rob S.]

Never worked on a bike clutch (changed the one on my '68 Camaro more than once), but it sounds like the plates are seriously glazed over, or worn out, or Teflon coated. I mean, no movement at all?

Maybe you could scuff them up.

[Agemax]

might sound like a dumb question but is the drive chain still attached to the sprockets, and is the front sprocket still attached to the output shaft on the gearbox?
After your "good hard ride" the nut may have come loose on the sprocket and it has come away from the splines

[zuluwiz]

Saw that happen one time "a few years ago". Got flagged down by a girl with a Honda Rebel 250 that wouldn't go. Started and ran OK, clutch seemed OK, took a look and the chain was off the rear sprocket. Weeeell........... I put the chain back on, it was still hanging 3 or 4 inches under where it should have been. I wasn't gonna tighten it up for them, I wasn't sure there was enough room to make it right anyway. Told em: "it aint safe to ride like this, just park it and take it to the Honda shop tomorrow and have them put a new chain on." Looked at me like I was talking Chinese or something. Got back on my XT500, went around the block, yup they were gone. Oh well, it's not my bike, and I sure aint gonna be the one to try and teach them about chain maintenance. Whoever sold her the bike shoulda told her. Maybe did, and she didn't want to listen.

[Guest]

Yes i did check that. Chain is fine and intact. Right where it should be

[Rijko]

Next step would be to take off the clutch cover and check if, with the bike in gear, spinning the rear wheel results in a rotating clutch.

[Guest]

It definitely does spin. I pulled the oil cap off yesterday and rolled it back n forth. The clutch definitely moves with the wheel.

[Guest]

As far as I can tell I don't think it's anything transmission wise. Everything still moves smoothly, I just don't have any clutch

[Agemax]

Something has broken somewhere, i fail to see how putting the wrong oil in will not cause the clutch to engage. You would have a slipping clutch maybe but not one that fails to engage at all.

[Baatfam]

Have we verified the clutch cable is actually moving the lever at the clutch end?
Looked through this thread, but didn't see that.

[rphillips]

Looking thru the oil fill hole, on a "77" 750, are you seeing the inner hub or outer hub (basket)? the outer hub should never turn unless the crankshaft is turning. If it does something is wrong in the primary, on the crankshaft or the outer hub. I can't imagine any oil, or oil additive, that can make a wet clutch slip that much. Also if pressure is same as usual at lever, the springs are pressing on the pressure plate & the clutch plates. This seems strange !!