3/4 Radial Master Cylinder vs 6 Pots

[zx12argh]

Is a 3/4 radial MC big enough for the tokiko 6 pots on my zx-12r.
I'm trying to bleed this sonofabitch but all I get it fuck all feel. Super spongey.

[Tony Nitrous]

Wouldn't know, but the "Brembo 19 RCS" was recommended to me for the Busa 6-pot's,
19mm.....3/4.... sounds close ?
I expect there's a lot more to it ? Caliper piston size's etc maybe ?
Busa 6-pot's are pretty average at best compared to later radial set up's.

[zx12argh]

Thanks Tony, you think I could find a spec on the 12r stock master cylinder? I wouldn't think the Busa would be too far off the mark from the 12r. I'll just keep trying to bleed these buggers I guess.

[Hagarr]

B-King Radials (just checked) has 3/4 master cylinder 4 spot.

As Tony says depends on volumes etc but have generally found the smaller the cylinder the harder the lever.

3/4 and six spots sounds like you should have a nice lever.

[Tony Nitrous]

Used braided lines, master cylinder straight to each caliper,
new quality fluid and a couple of different pads types.
Either of my Busa's brakes were borderline useable for "spirited riding"
A Brembo 19 RCS master cylinder was always going to be the next step.

B-King brakes, straight out of the crate with stock rubber lines etc
would put either of my past or current Mk1 Busa's 6-pot brakes to shame.

If that what modern radial brakes are like im sold on them.

[zx12argh]

I've got braided hel lines and new fluid. Just pulled the calipers off and can work the pistons by hand and no fluid is getting past the seals. I've just bled them again and it feels a little better. I've chucked a zip tie on with pressure on the lever so I'll see how it goes over night. Thought maybe I had undersized the cylinder but by the sounds of it, it should be right. Maybe I've still got an air lock somewhere.

[crazymofo]

Bin the calipers for either a set from a TLS1000 or a set from an RGV 250

cheers.joe.

[robmac]

Reverse bleeding is ur friend with these radial masters otherwise you spend alot of time getting no results. Once you get 99% of the air out then normal bleeding works fine.

[Large]

Pete, have you tried sucking the fluid through?

I got a 100cc syringe (ask a vet-tell em it's for a horse) and a bit of clear tubing and I can pull the fluid through from the bottom- or push it back up from the bottom and see where the bubbles are.

Dot4 enemas ftmfw!!1

[robmac]

And normally a 19x20 master is recommended for six pot calipers.

[zx12argh]

Any idea what size the 2003 GSXR 750 is? I know its a 3/4 bore but not sure what its stroke is.
I guess I could just measure it haha.

[Watto]

hey mate

sometimes bleeding brakes can be a pain in the ass might need to get the bleed nipples on the calipers higher than the M/C incase air is trapped - I've got an old rear brake disc i rest on my tank, put the calipers on either side and start the bleeding process - this generally sits the calipers above the M/C height and can bleed them in no time

hope it helps

[RevHead]

just a quick thought have u cracked the brake line up at the master cylinder to release the air that is always u there

[kroosn]

I've spent a fair bit of time with ZX12Argh trying to bleed this. We have tried reverse bleeding with a syringe, tried sucking it through and cracked it at every bleed nipple and banjo. I've had a few bastards to bleed with running a handbrake but nothing like this.

[oldskool]

Bleed from the top banjo.

[RevHead]

quote:Originally posted by oldskool

Bleed from the top banjo.
wot i said