Brake master cylinder sizes - Jap stuff
 

Just a little bit of info for the single minded ones..........


http://www.rg500delta.com/RG500_chas...re%20sizes.pdf

Good find Mike. I'll look out for a 1/2" jobbie now. :D

This has to be one of the most useful posts I've seen on here for years.

1/2" M/cyls were used on Steel framed CBR600s that had two calipers each having two pistons and of the sliding type, I always felt they worked well, Early Fireblades also used a 1/2" M/Cyl (there chart is wrong wrt to this one), in this case it was of the remote reservoir type and was connected to two calipers each with 4 pistons. The brakes on these early Blades I always found a beed weedy and upgraded mine to 5/8" (15mm ish) which did improve things.

When racing the TL1000SV which again came with two 4 piston calipers and a 5/8" Master, I upgraded to the GSXR 6-pot calipers and ended up going to a 3/4" (18mm ish) Nissin Master-cylinder before changing to a 20 X 19 Brembo Radial.
These days on both my 998s I have the AP adjustable ratio CP4125 M/Cyls as these allow you to dial in the feel that you want by adjusting the pivot point. Not saying I like my AP brakes but I'be been up to Leeds today and come back with a set of CP4466 6-pot calipers, CP4125 M/Cyl and some 320mm diameter 6mm thick race discs.
Quite a few modern bikes are now running 3/4" Nissin Radial M/Cyls with twin 4-pot calipers.

One thing that often gets missed is the position of the pivot point, the Brembo RCS has a couple of positions for it, the Magura has 3 I think and the AP has quite a range

I probably have 10 or more of my old jap bike M/cyls stored away, including several newer radial ones, I'll have to dig them out and see what I have.

bring some with you to Brands kev in case the Magura 16mm is way too much for one disc!!

Not got a spare rear master cylinder for Badger have you Skids?
Mines shot and Nelly thinks you'll probably have a spare one lying around.
(see for sale/wanted section)

anyone know what size the Multi front brake is?

another numpty (not Multi) question:
which is bigger 14mm or 5/8? Instincts tell me 5/8 is biggest looking at the bikes that are listed (and 1/2 being 13mm from dodgy memory)

5/8" = 15mm ish
1/2" = 12.5mm ish

So sizes as they go up are

1/2"
13mm
14mm
5/8"
16mm
18mm
3/4"

I'll see if I can dig some out tomorrow, but the main priority tomorrow is to cure the carb leak on my Class B monster, probably only a sticking float.
Also tomorrow I have to decide if I should connect up its second caliper or remove it along with the second disc

Some slight annomolies with Kevs sizing. :p

1/2" =12.7mm approx 13mm

9/16" =14.28mm approx 14mm

5/8" =15.875mm approx 16mm

11/16" = 17.46mm Nearer 17 than 18

3/4" = 19mm or as near as makes no difference. :D

Soory Kev just reread your post and it wasn't conversion but the size hierarchy

Phil my list is based on Master cylinders I have
I'm pretty sure they are in the right order

coolio, about what I thought, so must be learning something ;)

and Multi size brake? 16mm I suspect...

748/916 etc use a 16mm front brake m/cyl for operating the two 4-pot calipers they come fitted wirh as standard, I found fitting one of these to a single caliper didn't give me anywhere near the feel that I wanted

no different to what I have then, but if the magura is too much I may stick it on the multi if I keep it

guess i should look at a ZXR400 size instead just in case, although I found the 19x20 I had was fine and that wasn't that different with two calipers as a ratio than 16mm with one

And again the point is missed, its not just the piston diameter but the combination of the piston diameter and the lever ratio that also plays apart.

Magura recommend the 195 radial m/cyl with a 16mm diameter for bikes with two 4-pot calipers
Brembo recommend their 16 X 18 and 16 X 16 m/cyls for bikes using one 4-pot caliper

but Magura dont mention the lever ratio (that I've seen) and I assumed (maybe incorrectly) that most 16s will be the same ratio

I noticed on my 19x20 brembo that the closer to the bar the lever was set the softer and easier it was to pull and the magura seems to be the same. Is adjusteing the span adjuster making this affect? Also happens on Multi ones too...

Adjusting the span is just that, making the span fit your hand, if its closer to the bar its easier for you to pull, but doesn't change the amount of fluid you move, that is the same amount of mm travelled by the lever moves the Piston by the same amount as before say you pulled the lever in by 20mm the piston will have moved 4mm no matter where the span is set.

Magura quote a lever ratio of 1 to 5 for the 195 range (the one you have)
and they quote 1 to 7.2 for their 190 range of Radial Mastercylinders.

Brembo figures refer to Piston Diameter and Pivot point position

Had a little look earlier and among my Jap bike mastercylinders I have
3 X Nissin Radials all 3/4" piston size and all remote reservoir (Honda and Suzuki)
1 X Nissin Axial with 1/2" piston size and Remote reservoir (From a Honda)
1 X Nissin Axial with 5/8" piston size and Integral reservoir (From a Honda)

I should have a couple more out in the workshop as its not that long ago I upgraded the one on the R6 from a Axial to Radial caliper

Edited for you Kev. Master

Cheers Phil, I think I must have used up my Quota of that word for today

Still I have a nice set of PFM 6-pots, narrow track discs and a Radial thingy to go on the R6 this year, If I'm lucky i'll get around to swapping the cylinder head over on the spare engine and may even get that fitted into the bike.

Thinking of going over to the 4-pads on my DD bike, replacing the standard 620 issue 4-pots that are on it at the moment, I need something to try and help me out brake you guys on your lightweight bikes, the Brembo Radial will remain.