Clutch not fully disengaging

[KEH]

This is on a '99 M750. For some time (probably since I've owned it, for 3 years) now I have noticed the bike doesn't fully disengage the clutch, especially when cold. At a stop, when in first gear, holding the clutch, I can feel it pulling a little. Its fairly slight, but noticeable. Since owning it, I have replaced the clutch pack, which was slipping badly. I have also installed an Evolutionize slave cylinder. Of course, the new clutch made the problem more pronounced. Installing the new slave had no effect, good or bad.

I had it at the shop today and they noticed it too. They thought it may be the slave (which I don't think it is), the rod too short, or the clutch improperly installed. Back when I had the clutch apart to install the new discs, the basket looked brand new and nothing looked askew.

Any thoughts here? Could the rod be too short? If so, could I shim it up a little? What about the throwout bearing? Could it be a factor here? What about oil viscosity? I usually use Mobil One 15w-50.

Thanks in advance!

[He Man]

its a long shot, but the rod length changed at some point in the history of the monster so many of the slave clutch manufacturers will include a special nub that lengthens it. Maybe you didnt install this part? It happened on my 95 900, i coudlnt find that piece and ended up making one with a stack of shims.

Strangely, my current bike, an S2R1000 2006, is experiencing that problem right now. :/ it sticks and doenst want to disengage completely when its still cold.

What kind of oil are you using?

[KEH]

Thats interesting. I don't recall seeing any kind of nub. Do you know how I could find out what the correct rod length should be and if my bike requires a nub?

I usually run Mobil One 15w-50 oil.

Thanks

[He Man]

Thats interesting. I don't recall seeing any kind of nub. Do you know how I could find out what the correct rod length should be and if my bike requires a nub?

I usually run Mobil One 15w-50 oil.

Thanks

Is that Mobil one auto or moto specific 15w-50? because if its car oil, thats your problem right there.

[KEH]

Uhhhh....... Opppppps 

Let me go ahead and get that taken care of and see if that helps. I did not know there was a moto specific Mobil One, so when people were saying they used Mobil One I went down to Autozone and got some.

[Howie]

Some drag is normal on a wet clutch, particularly when cold.  Since both you and the dealer notice it as a problem, it probably is.  Anyway, if you noticed more drag right after the new clutch plates were installed, the problem could be the stack height is just a little high and the problem should diminish with time.  Is the slave a 28.5 mm or a 30.5mm bore?  The bigger the bore the shorter the stroke.  You can pull the slave and look for signs of leaking.  If it is leaking, Evo should take care of you on warranty.  At the same time, see if the push rod spins easily.  If it does, the throw out bearing is probably good.  They are usually not problematic on a wet clutch anyway.  Do bleed, bleed, and bleed some more since only a little air will cause partial disengagement.  When you are done bleeding, zip tie the lever to the bar over night.  The 15W-50 Mobil should be fine, even if it is car oil.  Energy conserving car oils can cause slippage with a wet clutch, but not your problem.  If you live up north in the cold country with winter setting in you might want to try 10W-40 if you are due for an oil change

[desmoworks]

This is on a '99 M750. For some time (probably since I've owned it, for 3 years) now I have noticed the bike doesn't fully disengage the clutch, especially when cold. At a stop, when in first gear, holding the clutch, I can feel it pulling a little. Its fairly slight, but noticeable. Since owning it, I have replaced the clutch pack, which was slipping badly. I have also installed an Evolutionize slave cylinder. Of course, the new clutch made the problem more pronounced. Installing the new slave had no effect, good or bad.

I had it at the shop today and they noticed it too. They thought it may be the slave (which I don't think it is), the rod too short, or the clutch improperly installed. Back when I had the clutch apart to install the new discs, the basket looked brand new and nothing looked askew.

Any thoughts here? Could the rod be too short? If so, could I shim it up a little? What about the throwout bearing? Could it be a factor here? What about oil viscosity? I usually use Mobil One 15w-50.

Thanks in advance!

I'll throw a few things out there for you... it is hard to help without seeing it, but maybe something below will help you diagnose it.

Ducati wet clutches like 10W40. If you use any "heavier" oil they are not as easy to find neutral, etc... as there is too much resistance with the oil flowing throw the plates. The slave cylinder is a larger diameter than your stock slave cylinder. It does not move the pressure plate as far as the stock slave cylinder does (that is why it has a lighter pull).

The pushrod on your bike is shorter than the newer Ducati motorcycles so you have to use a pushrod extension with any of the new slave cylinders - I assume you have this installed?

Some questions to provoke thought:
When was the last time you bled the air out of the entire clutch system?
What fluid are you using?
How old is the fluid?
Have you ever crashed the bike?
What is the clutch stack height?

[KEH]

Thanks for the great tips everyone! There is definitely not a pushrod extention in there, so I will get one. I'm sure that will help. I will also switch to 10w-40.

Thanks again,
Karl