Vintage Dirt Bike Q & A

After scrounging countless motorcycle salvage yards, I finally found a set of friction plates for my 79 cr125r. I was amazed as I saw the plates were measured under .01mm under the standard thickness. I picked up the whole set plus a near mint actuator for $35cdn.

The problem is that after I installed the plates, the clutch constantly sticks. My basket is fine and the pressure plate does fully disengage. The motor I salvaged them from was dry and when I installed them I coated them with the recommended 10W30. Should I have soaked them for longer?

Thanks
Elderstarr

First time I assembled my clutch I messed up the plate orientation. I should have paid attention so I wouldn't make the same mistake twice, but it was something like they only go together right every 120 degrees of rotation. That is, you have to keep rotating them until the slots line up exactly.

You should check the clutch basket to make sure it isn't grooved and hanging up the plates.

I also had the adjustment nut/screw that is on the clutch basket set wrong at least once. Vague recollection but the screw would hit the case before the clutch was fully disingaged. Clutch lever bottoms out before it reaches the handle bars.

Last but not least is I have had two bent clutch actuator rods on two different Sukies. Looked like someone had bent them into an 'S.

I had that problem on a cr 125 years ago.
I now soak them in oil 24 hours before assembly.
It should eventually be OK but you may try taping the clutch lever to the bar overnight.
As mentioned above, make sure your basket is not grooved. If it didn't do this before it isn't the basket.
As for filing the basket fingers, use a large flat file and you can dress two at a time 180 degrees from each other. Rotate one finger and repeat... and eventually you will have dressed all fingers. Do not get carried away doing this, it comes at a price.

Thanks for the quick replies.

My basket checked out fine, not a barb or groove for the plates to catch on. As for the orientation, my manual never mentioned that detail and I thank you for bringing that to my attention. Tonight I'll pull it apart again and soak the discs for a day, and this time line them up correctly.

Thanks again.

I had the same trouble a few years back on my Honda TL 125. After sitting a few days, the clutch would stick.Bike is very low mileage with original clutch.I was told to try several things one of them being to sand or sandblast the steel plates to roughen them up. The thing that worked was to change the oil. Seems that using a name brand automotive caused it. Switched to Honda 10-40 and bike can sit for a month or two with no sticking.

I don't know if this is relevent to your bike but on my 73 CR250 I had used a regular 6mm washer to hold down one of the clutch springs. Turns out the O.D. was a little bigger than the special washers called for. (Look the same on first glance. I didn't know there were special washers just for the clutch springs) This was causing the clutch to bind up a bit when I pulled in the lever.

Loren

_________________
Those who can make you believe absurdities can make you commit atrocities.

Loren Davis
51y

Ok... now I am clueless. I soaked the discs for a day and intalled them correctly and it still sticks. The pressure plate fully releases but the metal and friction discs stay stuck in a large mass. What gives? I can seperate them by hand, but other than that, they will stay stuck together. Could it be the springs are unevenly worn? My plates are fairly smooth, should I try to roughen them up as Gary suggested? If so, what grit?

Thanks again guys.

Elderstarr

No real clue but I have had that problem with wet/moisture on the plates. They soften and stick like glue, need a screw driver to separate them with the clutch pulled in.

Thing is if that was the case you would have had all kinds of clues like rust on the plates.

Not a spec of rust on the plates. I have had the clutch lever adjusted out all the way and taped down for 12 hours. There is tonnes of resistance but it does allow me to move the bike while in gear. This is really puzzleing me.

Man, tough one. I like it.

The old automotive AC compressors used carbon to ceramic rings to make a seal that was tight enough to keep in the freon molecues (sp). I mention this because maybe, just maybe your clutch is doing something like this. These two items, when oiled with AC oil, would stick together like glue if you tried to pull them apart. If you slid them apart, no problem. Like walking on ice. Maybe your fiber and metal plates are too smooth?
If you can afford to do this, use a piece of 40 grit sandpaper on a flat surface (glass, mirror...) and rough up the metal plates some. Clean them throughly and reassemble. If this works we know the problem. I hope this doesn't damage your plates but I did this on old clutches to get more life out of them in years past.
Just a thought, hope it works.

I think you hit the nail on the head there Rick. Yes, when I pulled the clutch apart, the plates did seem like they were sticking together, I thought it would go away when I filled the case with oil. I guess not. Thanks, I believe that was the answer I needed to hear. I'll try scuffing up the plates tonight and report back the results.

Elderstarr

Well... scuffing the plates did help a bit but they still feel like they want to stick together. There is less resistance but not complete release. The bike is not running at the moment but when it is, should I try letting the bike idle while in gear and the clutch is released? Would the friction discs overheat or will they seat onto the plates?

Elderstarr

So does anyone know why my friction and steel plates are acting like suction cups? Please help.

They shouldn't burn if you let it run in gear with the clutch pulled in. I always start the bike and ride it around for a minute and then expect the clutch to fully release.
I use Castrol 20w 50 in my race bikes.
I really think this will go away when warm after a couple of rides.
Keep us informed of the progress/cure.