MV Agusta Forum banner

1 - 20 of 23 Posts

·
Registered
Joined
·
83 Posts
Discussion Starter #1
I need to rebuild the clutch master cylinder on my 2013 1090RR Brutale.

Evidently rebuild kits are not specifically available for the bike. (Dealer standard operating practice is to just replace the master at around $600 USD. Presumably this is due to liability concerns.)

The Cylinder is manufactured by NISSIN, so I assume that one of the standard kits gaskets would work on the piston, but I cannot find the appropriate diameter kits. Has anyone ever faced the issue? Any input would be appreciated.

Robert
 

·
Super Moderator
Joined
·
21,486 Posts
Yes. This issue has been discussed ad infinitum before.

I believe Noel has found the correct diameter and seal parts.

Try search. Barring that, PM @theknurl.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #3
Yes. This issue has been discussed ad infinitum before.

I believe Noel has found the correct diameter and seal parts.

Try search. Barring that, PM @theknurl.
Just a status update for those interested:

Despite the "infinite discussion", I could find nothing definitive on the forum here on which kits or seals would be appropriate for the Brutale clutch master cylinder.

The bore diameter is 1/2 inch, but there are many different piston configurations (with their attendant very different seals).

After researching the the webs (a surprising dearth of specifics!) I believe that the K&L kit #32-4142, which is spec'ed for certain years of the Honda interceptor, will have the correct seals. Once I have the kit in hand I'll post the info.

Robert
 

·
Registered
Joined
·
820 Posts
Just a status update for those interested:

Despite the "infinite discussion", I could find nothing definitive on the forum here on which kits or seals would be appropriate for the Brutale clutch master cylinder.

Have to agree there. Lots of things here are discussed on here but can be pretty hard to track down given the headings on the posts. Can be hidden anywhere in search.

Cheers

Deano
 

·
Registered
Joined
·
14,226 Posts
?

Usually Nissin M/C bore sizes are marked on the underside.......
Most Hondas use 1/2"
K & L Supply will have the parts kit::wink2:
 

·
Registered
Joined
·
83 Posts
Discussion Starter #6
Usually Nissin M/C bore sizes are marked on the underside.......
Most Hondas use 1/2"
K & L Supply will have the parts kit::wink2:
Noel,

Thanks for responding.

Yes The bore is established at 1/2, but there are many different seal/piston styles that Nissan used in that size.

There are, to my knowledge, no cross references to the select the correct kit for the Nissan master that MV used, Even the photos that accompany the various kits advertised are stock photos that do not represent the actual seal types either.

I BELIEVE that I have found the correct kit number from K&L as mentioned above, and as soon as I can compare them side by side I'll report back.

Robert
 

·
Registered
Joined
·
23 Posts
Hey Robert & everyone.
Currently working on clutch issues which entailed sourcing seals for slave and perhaps master if becomes necessary. More on that in another post.

I have the K&L 32-4142 rebuild kit. Pics attached.

I am currently experiencing limited slave return.
I suspect the difference in the piston overall length is blocking the bleed-back port. K&L was very helpful but not able to find the replacement piston.
I will take it apart, (again) and try the seals on the original piston, (when I find it).

(Observation)
When pulling in the clutch repeatedly the slave cylinder is observed extending and returning
The return is not equal.
After a number of pulls the slave is extended to the point where the clutch plates are no longer pressed together.
Rear wheel turns by hand while in gear.
 

Attachments

·
Administrator
Joined
·
18,872 Posts
Those 2 pistons are NOT interchangeable. Yes, that is your problem.
 

·
Registered
Joined
·
23 Posts
Correct. The piston from the kit will not work. I will try the seals(from the kit) on the original piston.
It is likely the original piston is good and replacing the seals is all that is needed.

Separately, I am looking to determine how to increase the volume of fluid coming out of the MC. Any ideas would be welcome.
 

·
Administrator
Joined
·
18,872 Posts
Separately, I am looking to determine how to increase the volume of fluid coming out of the MC. Any ideas would be welcome.
The only way to accomplish that would be a new master cylinder..
 

·
Registered
Joined
·
23 Posts
Last night I was planning to test the new seals from the K&L kit on the original piston.
(Background: slave piston was not returning into slave cylinder causing clutch to remain engaged.)
I felt the problem was with the length of the replacement piston included in the rebuild kit.

In order to get the slave piston back into the slave cylinder before taking apart the master I bleed the slave at the master (through previously installed bleed port), then found the clutch engages and disengages.

Reinstalled everything, closed clutch cover filled with fluid and started bike.
With rear wheel off the floor, tire spins in neutral. Is this normal? Should I be concerned?

I feel so confused!
 

·
Super Moderator
Joined
·
21,486 Posts
There is friction between the components of the drivetrain even with the transmission in neutral.

If a slight drag of the hand on the wheel stops the motion, then you are fine.

If, on the other hand, the wheel is being driven hard, then you have an issue.
 

·
Administrator
Joined
·
18,872 Posts
Did you go back to the original piston with the new seals? If you still have the long K&L piston in there it is going to do the same thing as before after you ride it a few miles (clutch never engages, bike doesn't move).
 

·
Registered
Joined
·
83 Posts
Discussion Starter #14
Sorry for the lack of timely response. I have received the kit as well, though have yet to install. (I am waiting on the gasket for the MC res.)
I did not mean to imply that the actual pistons between the K&L kit and the original B4 MC would be identical, rather, I hoped, and still hope, that the seals from the kit could be used on the original piston. Your last post seems to confirm this?

Unfortunately the gasket I need is on back order. Motoforza in Escondido has no info on when it will come in. I will try to compare the seals fro the K&L kit with the originals tomorrow and update this.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #15
Correct. The piston from the kit will not work. I will try the seals(from the kit) on the original piston.
It is likely the original piston is good and replacing the seals is all that is needed.

Separately, I am looking to determine how to increase the volume of fluid coming out of the MC. Any ideas would be welcome.
As esq'z me observed, you would need fit another master cylinder. However, apparently one can, by replacing the slave cylinder, achieve better modulation with an easier lever similar to what I presume you are interested in accomplishing with a different master.

Unlike the clutch master which goes around $700 (US), slave upgrades can be had for around $100:

https://www.designcorse.com/products/mv-oberon-clutch-cylinder
 

·
Registered
Joined
·
83 Posts
Discussion Starter #16
I rebuild my clutch master cylinder this morning using the seals from the K&L kit # 32-4142.

I can confirm that the seal bearing surface dimensions between the two pistons (The K&L kit piston and the original MV) are identical.

After installing the new seals on my original piston, and bleeding the system, I have full clutch disengagement and excellent lever feel. I still lack the gasket for the res. so no road test yet.

The kit piston and spring are both longer than the original, and cannot be used.
 

·
Registered
Joined
·
23 Posts
I also installed the kit gaskets and feel seems smooth.
I will start it tomorrow to determine the drag. With the bike in 1st and clutch pulled in there was significant tension.

One of the complaints is the clutch is hard to pull. The kit spring is softer I hoped it would solve the stiffness problem for us. Unfortunately, I suspect it is not allowing enough fluid to get to the slave.

Rob, can you please compress and measure the spring that came with the kit? I would like to compare it to the original. Thank you.
 

·
Administrator
Joined
·
18,872 Posts
The spring won't change the feel so much...that is a function of the clutch springs and hydraulic pressure generated by the ratio of master to slave cylinders.....but if the spring is preventing full movement of the master piston you will not get full movement of the slave.
 

·
Registered
Joined
·
83 Posts
Discussion Starter #20
The spring won't change the feel so much...that is a function of the clutch springs and hydraulic pressure generated by the ratio of master to slave cylinders.....but if the spring is preventing full movement of the master piston you will not get full movement of the slave.
As usual, esq'z me is right. The clutch springs are substantially stiffer, and the ratio of diameters of the master to slave determine the mechanical advantage. The master spring is just enough to overcome the internal friction and the spring on the clutch switch.
 
1 - 20 of 23 Posts
Top