78 clutch not engaging

[westpat]

Hello all
Just bought a 78 standard that start and runs just fine. The guy I bought it from told me he put in a new R1 clutch. The bike will drive, but slips with greater throttle applied.
He said that after he rebuilt the clutch he filled the engine back to full with old oil from his Toyota corolla. He gave me 8 clutch rings to show me that he had done the work.
So he is either lying or confused. I only have 850 in the bike so I took a chance on him being confused.
I know the wet clutch can be finicky. What is the best process to find out if it is bad clutch or just bad oil?
Thanks for helping a newbie!
David

[Radioguylogs]

Can't believe the guy put old used oil in it. I'd change it immediately just to know something suitable is in it. 20-50W Castrol is popular among members here.

Next I would check the clutch actuator adjustment and the clutch cable adjustment. If you need help understanding what to do, just ask. It would be easy to imagine the clutch springs were not being released by tight adjustment. Does the clutch handle have any free play?

Lastly, you would need to pull the cover off the clutch and look inside. It can be done without draining the oil if you put the bike on the kickstand (not the centerstand).

[westpat]

No slack in the cutch, but it does not take much grip pressure to disengage it.
Seems a little soft to me overall.
David

[DiverRay]

Number one problem behind the wrong oil is old clutch springs. It seems that Barnett springs do the best job, with stock #2 and everything else a distant third. I'd go that direction after checking the easy things..

[TopCatGr58]

Hey there,

Good info already. With very little action/no slack needed to actuate the lever, there's a good chance that you need to adjust the throwout rod under the smaller inner clutch case cover...with 2 philips screws. Under there you'll find the throwout lever arm and the throwout rod with a lock nut and set screw. The manual describes how to adjust it. Just make sure you have enough cable slack at the handlebar first so that the engine leve isn't already under tension. Then unlock the nut using a box end wrench...then hold it in place while first turning the center philips screw/rod out a turn or so..then turn it back inwards....clockwise until it just makes contact with the throwout bearing.....then turn it back out CCW a 1/4 turn, then lock the nut, and then test the lever...readjust the handlebar slack to allow about 1/4" of space at the lever, and then it should be good.

IF the throwout adjustment is too tight....and can get that way from use as the friction plates wear....then the rod will be keeping the pressure plates from fully squeezing the frictions/steels for the strongest grip.

And then has been stated....new springs...especially IF the PO didn't replace them when he did the friction plates! And the old automotive oil especially if it was synthetic would have friction modifiers...the lower portion of the API seal would have stated such....and these are also known to contribute to clutch slippage....especially with a marginal condition clutch ie....weak springs and worn frictions.

T.C.

[Rasputin]

Another thought would be that the cable itself is sticking. Be sure that you lube the cable, as I once had a slippage issue that was due to that cable and not the actual clutch.

[westpat]

Thanks so much for all the info. I have my work cut out for me. Will start with an oil change and move on from there, cables, springs, etc.
Will report back.
David