Clutch master cylinder question

[Elimax]

Hi all:

I hope all of you had a great New Year's Eve and are ready for 2014!

I've got a question about clutch master cylinders...I'm basing this question on the fact that different brake master cylinders exert different "fluid pressures".

Can any of you recommend a "powerful" clutch master cylinder that would improve clutch performance of a standard UJM clutch master cylinder?

(I'm basing this question on the fact that I'm rebuilding a '94 Honda CB1000...after replacing the clutch friction plates, steel plates, and springs with Barnett parts, I find the oem master cylinder's performance is sub-par.)

And by the way, my Max is still kickin' ass!

Thanks for your help!

Elimax

 

[[email protected]]

Hard to say without knowing the stock master cylinder size on your honda.

And by more powerful, what do you mean? Are you looking for something that takes less effort to pull or more effort?

Generally, a larger master will have a firmer lever. Smaller will have a softer lever.

Larger will cause the clutch pushrod to move further with the same lever movement. Too small of a master will not fully disengage the clutch.

Think of a simple lever setup.



You are pushing down on one side, the pivot point is in the center, and a 100LB weight on the opposite end. Now, move the pivot point closer to the weight. When you push down on the lever it takes less effort to raise the weight but, you cannot raise the weight as high as you can with the pivot point in the middle. A big master is equivalent to the pivot point in the middle. A small master is equivalent to having the pivot point closer to the weight.

 

[Elimax]

Thanks for the reply...that image was helpful.

The firmness of the lever is not an issue to me...hell, I run the double D clutch mod on the Max!

I'd really like to find a larger master...more firm is fine, as long as it fully disengages the clutch. I suspect that the master cylinder I'm currently running isn't fully disengaging the clutch.

So, any recommendations for what might meet the requirement?

Thanks again.

Elimax

 

[[email protected]]

I find it hard to believe the OEM spec'd a master that doesn't work properly. Unless you don't have the stock master/slave/clutch geometry.

Is the master in good shape? What about the line and slave cylinder? I'm not familiar with the CB you have but, after working on other bikes I've found a few causes of disengagement issues. Pushrod arm is worn (doesn't apply to hydro clutch but, think slave cylinder) pushrod is worn, missing ball bearing in pushrod assembly, worn throw out bearing, improperly aligned pressure plate, notched clutch basket...

If the above checks out and you still feel the need for a different master I would suggest something that has a bore no more than 2mm larger than what you have.

 

[Elimax]

Okay...

So how do I find out what bore size my current clutch master cylinder has? Any recommendations where I might find this, or how I can calculate it?

Failing that, how do I find out the bore sizes of master cylinders of other bikes out there?

Thanks!

Elimax

 

[Elimax]

Anyone? I need help with this!

 

[Rusty McNeil]

I think it'll have the bore size on the body somewhere in fractional English numbers. As in "5/8" for 5/8" etc.

 

[marsmax85]

You might try v4musclebike .com might be some one there that can help ?