Bloody Brakes!!

[Talking Heads]

It works by allowing the trapped air to move to the top from where it is easier to got rid of.

[Mickle]

Originally Posted by Talking Heads

Pull the brake lever fully on, strap the lever to the handlebar then leave it overnight ensuring the master cylinder is at the highest point and above all the run of hose.
In the morning slowly release the brake lever but do not pull the brake lever again until you have manually pushed the pistons back into the calipers.
Once the pistons are back in the calipers bleed the brakes as normal.
Et voila, brand new brakes.

Plus one on that also I unbolted the splitter block under the lower yoke ( leave the hoses on ) twisted it so the master cylinder hose is upper most and gave it a good shake so any trapped air rose to the master cylinder

[SV650rules]

I certainly don't understand how tying the lever back will get air out of the system, as Bibio says all it does is compress the air, but unless the compressed air somehow manages to sneak passed the seals during the night it will still be there in the morning. There is a equalization port on the master cylinder that is only uncovered when piston is fully retracted, the purpose is to let air out and fluid back in, in other words brakes are designed to bleed themselves every time you use them. If the piston on your master cylinder never gets fully retracted or this port is obstructed then brakes will not self bleed.

[21QUEST]

Tying the lever back (not too tight) does work....don't ask me about the science but it does work.

Back to issues with bleeding bleeding brakes.
Provided the calipers have been rebuilt properly , *insert own words* etc and other company of the braking system are in order, 9/10, any difficulty is to do with the upper part of the braking system.
That is to say, the master cylinder needs to be bench bled....fancy way of saying, 'air trapped in master cylinder.

What usually one needs to do is, pump the lever a few times, hold it back and crack open the banjo bolt to let ut the air trapped. Make sure you tighten (not fully yet) the banjo bolt before lever comes back to bar..

Do that 3-4 times and then bleed as normal....caliper furthest from master cylinder first.
I'd usually bleed each side twice and job done.

Oh as someone(Bilbo) mentioned, if the pads eg new pads needs to bed to discs, the brakes will feel bit even after having been bled properly.
That said, even if that were the case, the lever should come back to the bar.

[650]

Nobody has mentioned the obvious thing here...the master cylinder size. You can't just whack a MC on and think it'll do the job. If it's too small then it'll result in long lever travel, too big and it'll result in virtually no travel with a wooden on/off feel.

What size is the standard MC?

What size is the Brembo, is it radial or axial? What bike is it off?

The brakes on a 650 aren't magical by any means but you should be able to lock the front up with a good squeeze of the lever.

[egcSV650s]

Originally Posted by 650

Nobody has mentioned the obvious thing here...the master cylinder size. You can't just whack a MC on and think it'll do the job. If it's too small then it'll result in long lever travel, too big and it'll result in virtually no travel with a wooden on/off feel.

What size is the standard MC?

What size is the Brembo, is it radial or axial? What bike is it off?

The brakes on a 650 aren't magical by any means but you should be able to lock the front up with a good squeeze of the lever.

The brembo mc i have is made for the sv650 it was brand new but there is different bore sizes, 18,19 and 20. Its on 19 at the moment which is what it came like but not sure about what one to put it on as you can change it

[650]

You need to work out the ratio, on a radial (as it sounds like it's an MCS...which isn't made for the SV, it's just a general one size fits all unit) the ratio needs to be around 130:1 to 135:1 to have decent lever travel and feel. There's a calculator available that a chap made a while back.

It was originally an XLR file but I've edited it to be a standard Excel file. It can be downloaded here: https://www.dropbox.com/s/pvouln3vre...ator.xlsx?dl=0

You'll need to know caliper piston cylinder sizes, lever to pivot distance...so on and so forth. Leave the 'mid piston' section as 0 and fill in the 'small piston' for the smaller SV piston size.

Regarding the lever to pivot, the info is available from Brembo, but I've copy/pasted it here for you to see:

The RCS system consists of an adjuster that sets the brake lever pivot distance to either 18 or 20 mm, for the perfect feedback between rider and machine: setting the pivot distance to 20 mm makes the braking system more reactive and immediate, while a pivot distance of 18 mm makes it more precisely controllable.

Changing between the two settings is extremely quick: simply adjust the master cylinder pivot distance by turning the adjuster on the front of the guide lever with cam mechanism by 180° using a screwdriver (red indicates 18 mm, black indicates 20 mm). This changes braking power distribution without modifying the pure power of the system itself.

The piston, gaskets and push rod of RCS master cylinders are exactly the same components as those in the master cylinders used by practically all MotoGP and SBK riders, and are manufactured to extremely fine tolerances and ensure very low friction.

The lever consists of two main components: the racing lever guide and the folding, forged lever itself.

With this you should be able to work out a suitable ratio to give good lever travel and feel.

On the topic of bleeding, if it is in fact an RCS19 that you've got, then you have a bleed valve on top of the lever body as well, air can easily get trapped here so it's worth investing in a one way bleed valve so you can happily pump away without having to repeatedly open and close the valve.

Hope this helps!

[egcSV650s]

Originally Posted by 650

You need to work out the ratio, on a radial (as it sounds like it's an MCS...which isn't made for the SV, it's just a general one size fits all unit) the ratio needs to be around 130:1 to 135:1 to have decent lever travel and feel. There's a calculator available that a chap made a while back.

It was originally an XLR file but I've edited it to be a standard Excel file. It can be downloaded here: https://www.dropbox.com/s/pvouln3vre...ator.xlsx?dl=0

You'll need to know caliper piston cylinder sizes, lever to pivot distance...so on and so forth. Leave the 'mid piston' section as 0 and fill in the 'small piston' for the smaller SV piston size.

Regarding the lever to pivot, the info is available from Brembo, but I've copy/pasted it here for you to see:



With this you should be able to work out a suitable ratio to give good lever travel and feel.

On the topic of bleeding, if it is in fact an RCS19 that you've got, then you have a bleed valve on top of the lever body as well, air can easily get trapped here so it's worth investing in a one way bleed valve so you can happily pump away without having to repeatedly open and close the valve.

Hope this helps!

Wow thats alot of info lol, ill have to get all the measurements and try it out, i might change the pivot distance to 20 and see how that feels but i do have a one way bleed valve so will give that another go. Thank you for all the info appreciate it

[650]

It looks like a lot, but it's not really. You just need the diameter of the pistons on the SV sliding calipers. The Brembo information is easy to input as it's in that quoted box. Then you can play with the Brembo to get that magic ratio. If the magic ratio doesn't work, then it's an issue elsewhere - air in the lines still (the lever being closed on a radial with a top bleeder won't work as it would with an axial MC) or the Brembo just isn't a good match for the sliding calipers (in which case, I might buy it off you if you want rid, as I've been eyeing them up). I think the standard MC size is 5/8? It'll be stamped on the cylinder body if you still have it.

[egcSV650s]

Originally Posted by 650

It looks like a lot, but it's not really. You just need the diameter of the pistons on the SV sliding calipers. The Brembo information is easy to input as it's in that quoted box. Then you can play with the Brembo to get that magic ratio. If the magic ratio doesn't work, then it's an issue elsewhere - air in the lines still (the lever being closed on a radial with a top bleeder won't work as it would with an axial MC) or the Brembo just isn't a good match for the sliding calipers (in which case, I might buy it off you if you want rid, as I've been eyeing them up). I think the standard MC size is 5/8? It'll be stamped on the cylinder body if you still have it.

Ill have a look tomorrow at all that info and see what i can do, if i want to get rid of the brembo mc if it doesnt do anything then ill bare you in mind that you might want it, ive still got my original sv mc and also got a gsxr750 mc that i put on to see if it made it better but didnt really