View Full Version : DIY - Installing a ZX-6R Master Cylinder


VeX
December 12th, 2008, 05:57 PM
I know this is going to stem a good 10+ posts of people asking if they should do this to their bike, but I digress:

Anywho, I don't like the slop in the stock master-cylinder and wanted to convert to Pazzo levers on the clutch AND brake side... That was the initial mindset. I also wanted to convert to Galfer SS brake lines. I figured I might as well just switch out the whole master cylinder/lever with a ZX-6R's (Which stock is an adjustable lever). So to begin:

Step 1 - Get the parts!

Here are the master cylinders next to one another:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/MC_Comparison.jpg
Fun story time: I got the 2007 ZX-6R master cylinder and lever (bottom) but it lacked a reservoir. I then got a reservoir from a ZX-7R (which CAME with it's master cylinder) (top) :p . It was only $20 which is a steal considering a NOS M/C for the ZX-6r is around $60 . Lastly in the middle is the factory 250r mastercylinder and lever.

Top and bottom view of the ZX-6r M/C:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/MC_ZX6.jpg
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/MC_ZX6-Underside.jpg
Notice the brake hose mounts underneath the M/C whereas the 250r's mounts on the front? This leads to...

The tale of the two hoses:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Two_Brake_Lines.jpg

The shiny Galfer line makes the factory line look like a chump. Here's the important part:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Two_Brake_Lines-3.jpg
The caliper side maintains the same angle (although look how much more compact and nifty the Galfer one appears).

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Two_Brake_Lines-2.jpgb
For the M/C side I ordered the hose with a 90 degree bend. This allows it to mount without incident except for one little hiccup which I'll go over shortly...

Step 2 - Loosen the reservoir cap.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-2_Loosen_Reservoir_Cap.jpg
This allows for the draining of the brake fluid.

Step 3 - Hook up a vacuum pump to the bleeder valve, open the bleeder valve and pump the lines clear.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-3_Flush_Line.jpghttp://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-3_Flush_Line-B.jpg

Step 4 - Remove the banjo bolt
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-4_Remove_Banjo_Bolt.jpg
Make sure to have a rag when you do this. The traces of brake fluid might form a drop or two and you don't want that stuff on paint!

Step 5 - Remove brake hose clamp
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-5_Remove_Brake_Line_Clamp.jpg
Follow the line up and on the triple tree clamp is a brake line clamp. One 10mm bolt holds it in place.

Step 6 - Remove the M/C brake line banjo bolt
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-6_Remove_MC_Banjo_Bolt.jpg
Same as the lower, make sure you have a rag handy... The hose should come out with ease.

Step 7 -Remove the old M/C
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-7_Remove_Brake_Bracket.jpg
Remove the cap (Should be two-8mm bolts), and swing the M/C up so that you can:

Step 8 -Remove the brake sensor
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-8_Remove_Brake_Sensor.jpg
One phillips screw holds it on...

Step 9 - Put the new M/C on
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-9_Installing_MC.jpg
Same as the 250r M/C except (2) allen head bolts attach the M/C to the handlebar. Here's one snag to the installation of this M/C. The way the brake hose mounts to the M/C on the bottom you can't swivel the assembly down like the old one. So it sits higher than the original. It's not THAT noticeable IMO, but I haven't really figured a way around it. The picture of this problem is in step 15. Also the brake sensor fits perfectly on the new M/C! It's clocked a little differently, but mounts the same way.

Step 10 - Making a reservoir mount.
In the last picture I was simply holding the reservoir up. To mount it I:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-10_Fit_Bracket.jpg
Cut a piece of 3/4" flat aluminum stock (about 2" long). The top of the bracket is notched so the aluminum slides up and 'seats'. I put one #10 sheet metal screw through the original bracket and the aluminum. I then attached the aluminum piece to the handle bar mounts (see the holes?).

Step 11 - The reservoir attached:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-11_Reservoir_Installed.jpg
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-11_Reservoir_Installed-B.jpg
I'll paint the aluminum flat-black one of these days, but no matter. From the front you can see the original reservoir bracket attached to the aluminum with the sheet metal screw. You can't see the bracket much from the other side. I'll eventually get a new hose, but this one works surprisingly well (no kinks). I spun the M/C inlet forward and the reservoir inlet faces forward. So the hose makes a 'U'. I mounted the reservoir just high enough that there are no high spots on the hose (no place for air bubbles to form) and a dumb stroke of luck it is pretty level! :p

Step 12 - Preparing the new hose.
I reused the clamp from the original brake hose (to attach it to the lower triple tree clamp) and the grommet.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-12_Remove_Rubber_Grommet.jpghttp://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-12_Remove_Rubber_Grommet-B.jpg
I cut a line along the grommet (there are seam lines on the grommet, so cut one of them). The grommet can then be peeled from the original hose.

Step 13 - Install the grommet.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-13_Install_Grommet.jpg
Nothing complicated here. The grommet slips over the new hose and you can bend the clamp back over it. Since the OD of the Galfer hose is thinner (SS lines are stronger AND thinner) the grommet doesn't 'clamp' the hose. You can plausibly wrap the hose with electrical tape to make up the gap, or you can just not sweat it (I'm not too worried).

Step 14 - Install the hose.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-14_Install_Lower_Hose.jpg
First connect the banjo fitting back on the caliper. Make sure you route the hose back through the brake hose guard (look about 3" up the picture). The new Galfer line includes new crush washers AND a new banjo bolt (sweet!)

Step 15 - Finish hooking up the line.
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-15_Install_Upper_Hose-B.jpg
You can see here the hose clamp back installed. A few other 'points of interest'... See the 'slack' portion of the hose (between the lower triple tree clamp and the caliper)? The major 'unexpected' part of this was the clocking of the 90 degree banjo fitting atop the hose! The way it's clocked I had to spin the line around about 180 degrees and that's why there's a 'corkscrew' at the bottom :mad:. I'm not entirely happy about that, but then again it shouldn't cause any problems. It just looks stupider than it should.

Also you'll see the zip-ties holding the brake line to the fork tube. The brake line will contact the plastic cowling around the fork tube otherwise. Since the area of the forks between the two triple tree clamps doesn't 'move' it's a safe spot to clamp to.

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-15_Install_Upper_Hose.jpg
At the top of the hose you can see the 90 degree banjo fitting attached. Again it includes a new banjo bolt and crush washers (yeah!). Circled in green is the spot where the M/C contacts the throttle cable. As previously mentioned this is what causes the whole assembly to have to sit a little higher than previous. I actually clocked the clutch lever assembly up a little as well to ensure things don't looks 'dumb' :thumbup: Whenever I lube my throttle cable I'll see about clocking the throttle assembly down a little and then I can move the M/C down :rolleyes:

Step 16 - Bleed the lines.
Fill the reservoir with brake fluid. Just like flushing the line, do the same thing from step 2. This time pump until brake fluid comes out.

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Step-16_Bleed_MC.jpg
With this style M/C there's a bleeder ON the M/C (neato!). I hooked the pump up and pulled the air out of that one as well.

Little micro-bubbles always find their way into the system and it takes some time for everything to settle into normal bubbles. So I usually wait an hour or so and then re-bleed. Pumping the brakes a lot helps with this!

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/MC_Installed.jpgHuzzah! You can see it pretty well in the last picture as well. All in all I think it looks pretty flipping sweet. It looks nifty and the tolerances are real tight (no more slop!). I can't wait to go and... Stop! :D

kkim
December 12th, 2008, 07:56 PM
Great job!

So, the only way to avoid the twist in the line is to specify how the top fitting should be attached to the line when they make it? Is there even a provision for that when you order the custom line?

Curious to hear the road test results once you get to test.

Kudos to you for even hatching up the idea to mount up parts from another bike and to have success the first time around. :thumbup:

Pictures of stoppies would be appreciated. :D

VeX
December 12th, 2008, 08:12 PM
Great job!

So, the only way to avoid the twist in the line is to specify how the top fitting should be attached to the line when they make it? Is there even a provision for that when you order the custom line?

Curious to hear the road test results once you get to test.

Kudos to you for even hatching up the idea to mount up parts from another bike and to have success the first time around. :thumbup:

Pictures of stoppies would be appreciated. :D
:happy110: Actually that's a good bit of logic! To get a wheel off the ground, rather than re-sprocket or get more power, I'll just upgrade the front braking and get that rear wheel off the ground! :thumbup:

They have a whole form you can fill out and they accept faxes where you literally DRAW what you want! I didn't really consider this though ahead of time... With all the stainless braided systems I've done I've used removeable AN fittings. So this is the first time I've run into this problem hah.

kkim
December 12th, 2008, 08:19 PM
what was the cost of the custom line? hindsight is always 20/20, eh? :asshat:



thanks for being the guinea bunny on this!
:bunnycake:

VeX
December 12th, 2008, 08:22 PM
what was the cost of the custom line? hindsight is always 20/20, eh? :asshat:



thanks for being the guinea bunny on this!
:bunnycake:

The regular line is $55, to make it 'custom' there's an additional $5 fee :thumbup: . If I had money I would've also sprung for the rear line (along with the EX500 perch and pazzo clutch lever), but I digress :happy110:

kkim
December 12th, 2008, 08:24 PM
The regular line is $55, to make it 'custom' there's an additional $5 fee :thumbup: . If I had money I would've also sprung for the rear line (along with the EX500 perch and pazzo clutch lever), but I digress :happy110: sounds like you need to stand in line in this thread. :p

http://www.ninjette.org/forums/showthread.php?t=10610

VeX
December 14th, 2008, 11:32 AM
:lol: I haven't really been able to try out the new M/C. Just a quick jaunt to the gym yesterday, but it was raining so I didn't want to 'test' it :p . That and I never got around to re-bleeding everything after everything's had time to fully settle... Anywho I re-clocked the throttle assembly and was able to set everything better:

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Drill_Hole.jpg
After opening up the throttle assembly I drilled a hole slightly lower than the original 'alignment' hole. This allowed me to set the throttle housing clocked forward a bit... One additional perk to doing this was:

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Re-Route_Throttle_Lines.jpg
The throttle cables are routed in front of the shock tube. It's a sharp bend, and now I was able to route the cables behind the shock tube. The bend is a lot less sharp now as evident in the adjustment knob on the throttle housing. It's not being 'pulled' forward anymore. Yeah!

But wait! There's more:
http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Re-Clocked-1.jpg
This also allowed me to turn the banjo fitting on the bottom of the M/C so now it not only completely clears the black cowling around the dash area, but it lessens the corkscrew effect on the brake line!

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Re-Clocked-2.jpg
It's damn near straight and from the outside it no longer looks 'odd'. :thumbup:

http://i291.photobucket.com/albums/ll294/VeX86BirD/Master%20Cylinder/Angled_Down.jpg
So I rotated it down and spun the clutch lever back down as well so it's all as it should be. :whoo:

workdaddy
December 14th, 2008, 12:23 PM
Great Write Up Vex... Kelly... He's catching up to ya on stuff like this

VeX
December 14th, 2008, 12:51 PM
Great Write Up Vex... Kelly... He's catching up to ya on stuff like this

I'm hoping Kelly stops spending so damned much time working and making money to SPEND some of that money and making more DIY's! :D

My upcoming DIY's should be:
Changing to an EX500 clutch perch and Pazzo clutch lever
Installing a new chain and pressing on the master link
Changing the brake pads
Installing clip-ons
and eventually the "Adding extended intake runners"

Then again I don't have any money so it's going to be a while possibly until I start doing anything :D I'd LIKE to also tackle putting an aftermarket gauge cluster and making a fiberglass enclosure for it, but that's really expensive compared to most anything else. Perhaps that's an idea for things people can do write-ups on as well?

kkim
December 14th, 2008, 01:08 PM
I'm hoping Kelly stops spending so damned much time working and making money to SPEND some of that money and making more DIY's! :D

My upcoming DIY's should be:
Changing to an EX500 clutch perch and Pazzo clutch lever
Installing a new chain and pressing on the master link
Changing the brake pads
Installing clip-ons
and eventually the "Adding extended intake runners"

Then again I don't have any money so it's going to be a while possibly until I start doing anything :D I'd LIKE to also tackle putting an aftermarket gauge cluster and making a fiberglass enclosure for it, but that's really expensive compared to most anything else. Perhaps that's an idea for things people can do write-ups on as well?

unfortunately, we had someone just go on a 3 week vacation, so I'll be having 12-16 hour days to cover the gap his absence has left. :( ho-ho-ho... so much for a merry christmas.


good to see you've got a host of things lined up... and good to see your list has nothing on it that I'm lined up to do in the near future, so that means there will not be overlapping of DIYs.

I really don't care who "wins" the DIYs "race". As long as the result is that we all end up winners by the knowledge shared, I'm good with that. :)

workdaddy
December 14th, 2008, 01:13 PM
I feel ya... See I keep seeing all these nice DIY's and think I would love to do that... Ahh Crap. I have no money:( so I will just wait and then come back to you guys when I do ever get it;)
Lookin forward to the upcoming thread on DIY's Vex:thumbup:

kkim
December 17th, 2008, 11:29 PM
Okay... feedback, Vex!!! How is the front brake? :boink:

VeX
December 18th, 2008, 01:13 AM
Low and behold it doesn't rain for like 6 months (I'm not exaggerating) and it's been raining non-stop for about 3 days now :mad: The weather forecast has been this: http://i.imwx.com/web/common/wxicons/45/11.gif

Finally tomorrow it should be letting up. I rode to the gym last night as it was a light sprinkle (and got rained on like the dickens on the way back), but I haven't really been able to get a good feel for the brakes. It is definitely a LOT more responsive now! It's not like you grab the lever and you endo :p . The total distance you have to move the lever isn't much and (likely because the SS line) there is no sponginess! :thumbup:

kkim
December 18th, 2008, 01:25 AM
yeah, I saw where you guys in socal were getting some cold, rainy weather.

geeez, snow in las vegas, even. :smow:

it's somehow connected with the weather we're having here, too... rain for the past week. grrrr... pic of the GF and me > :rain::rant:

keep us updated once you're doing stoppies!

HKr1
December 19th, 2008, 03:22 PM
Dude over on the other forum(redelk) did this with a 04 ZX-10r MC.

Maybe will do this one also..........


Pazzo lever rocks for the clutch :thumbup:

For the clutch lever perch. If I was doing it over, I would look for a newer style perch...... something smaller/newer than the old style ex500 :)

VeX
December 24th, 2008, 04:35 PM
Dude over on the other forum(redelk) did this with a 04 ZX-10r MC.

Maybe will do this one also..........


Pazzo lever rocks for the clutch :thumbup:

For the clutch lever perch. If I was doing it over, I would look for a newer style perch...... something smaller/newer than the old style ex500 :)

Wow. I like to see variations in theme :) What forum is that on?

ALSO: I'd been under the impression that Galfer lines do not swivel. I was looking something up on their site and the fittings DO swivel! They're really tight so they can't swivel freely, but I was able to pad some channel locks and swivel the fitting. So now the line is str8!

Alex
December 24th, 2008, 05:56 PM
Hmmm... I've got a ZX-10R master cylinder ('06) sitting in the garage because I swapped it for a Brembo on mine. Might as well take a look-see to figure out if a swap with the ninjette's is worth it. Though to be honest, the 10R m/c is a pretty low-quality piece, which is why the Brembo is necessary anyway. Believe it or not, Kawi put a better m/c on the 6R's than the 10R's the past few generations. Can't speak for the new '08 10R m/c, but it's supposed to be improved.

VeX
December 24th, 2008, 08:22 PM
Hmmm... I've got a ZX-10R master cylinder ('06) sitting in the garage because I swapped it for a Brembo on mine. Might as well take a look-see to figure out if a swap with the ninjette's is worth it. Though to be honest, the 10R m/c is a pretty low-quality piece, which is why the Brembo is necessary anyway. Believe it or not, Kawi put a better m/c on the 6R's than the 10R's the past few generations. Can't speak for the new '08 10R m/c, but it's supposed to be improved.

:lol: Actually I DO believe it! That's one reason why I got the 6r master cylinder. A really common upgrade on the '06+ 10R's is to put 6R or 14R calipers on (They use the SAME Nissin caliper!). I don't know why, but Kawi dropped the ball on the brakes on the later 10R's!

Alex
December 24th, 2008, 10:09 PM
:rolleyes:

http://www.ninjette.org/forums/showthread.php?t=11176

:D

Yup, I've seen folks put on the ZX-14 calipers, had not seen them swap out for the 6R calipers and wasn't aware they were the same. The 14 calipers are much heavier than the 10's; the 14 uses steel pistons and the 10's are aluminum. But the 14 calipers do provide better braking power and feel. On my 10 I put on more aggressive pads, steel lines, and the Brembo m/c, and kept the stock calipers; those changes were enough for decent performance at my current skill level. At some point if I can find some 14 calipers (or now it sounds like 6R calipers) cheap, maybe I'd add them on as well...

ken_here
January 16th, 2009, 01:55 PM
I hope its Ok top add a side note to this thread of a steel braided line install that might help others out here (http://cycleposers.com/index.php?option=com_content&task=view&id=488&Itemid=44)

thought it had some good pictures.

IF not... mods delete please.

VeX
January 16th, 2009, 06:20 PM
ehh I don't like some of the things they did in that article. I would suggest opening the reservoir and draining the brake fluid out of the bleeder screw on the caliper. In that article they just loosened the banjo-bolt on the caliper? That'll pour brake fluid all over the place! That and it'll force the rubber diaphram inside the reservoir to expand un-nessesarilly.

rabies
October 25th, 2012, 11:57 AM
bumping from the grave. so does the 08+ ninja 250 "lever" work with this bmc?

alex.s
October 25th, 2012, 12:29 PM
Kevin2109 probably knows

g21-30
October 26th, 2012, 10:15 AM
bumping from the grave. so does the 08+ ninja 250 "lever" work with this bmc?

Nope! :thumbup:

Kevin2109
October 27th, 2012, 09:13 AM
bumping from the grave. so does the 08+ ninja 250 "lever" work with this bmc?

nope, you will need a new lever, or if you have aftermarket already (the good ones, like CRG) you can replace just the part that attaches to the master


I have a 2006 Master cylinder if anyone is interested

falonso0
November 19th, 2012, 05:38 PM
Hi! I'm fernando from Argentina. I recently installed a Zx6 07/08 pump on my ninja 250 2009 but when tested the lever is very strong and brake a half of the axial original pump.. Do you have some suggestion??

Galaxieman
November 19th, 2012, 06:22 PM
Hi! I'm fernando from Argentina. I recently installed a Zx6 07/08 pump on my ninja 250 2009 but when tested the lever is very strong and brake a half of the axial original pump.. Do you have some suggestion??

If the air is bled out of the brake line, there should be much less movement at the lever, since the new MC pushes more fluid so it takes less lever pull to build the same pressure in the line.

As another aside, I swapped the stock MC from my '02 Superhawk (I had upgraded that to a 954 MC) and the same result: Hugely improved feel at the lever, much less pull, and much more immediate brake response. I still need to do an upgraded SS line and get some better pads put on, but just swapping the MC moved the front brake up to 'satisfactory' from deep in 'full-on sketchitude' territory.

falonso0
November 19th, 2012, 06:27 PM
Hi! I'm Fernando from Argentina. I recently installed a Zx6 07/08 pump with GALFER lines and Ipon dot4 brake fluid in my ninja 250 2009 but when tested the lever is very strong and brake a half of the axial original pump.. Do you have some suggestion??

falonso0
November 19th, 2012, 06:37 PM
If the air is bled out of the brake line, there should be much less movement at the lever, since the new MC pushes more fluid so it takes less lever pull to build the same pressure in the line.

As another aside, I swapped the stock MC from my '02 Superhawk (I had upgraded that to a 954 MC) and the same result: Hugely improved feel at the lever, much less pull, and much more immediate brake response. I still need to do an upgraded SS line and get some better pads put on, but just swapping the MC moved the front brake up to 'satisfactory' from deep in 'full-on sketchitude' territory.

Ok I understand thanks but my problem is not the pull distance, my problem is the strong pressure to pull to have the same brake response of the original.. It’s dosen't stop líke before.. Can I do smething to fix it?

falonso0
November 19th, 2012, 06:42 PM
If the air is bled out of the brake line, there should be much less movement at the lever, since the new MC pushes more fluid so it takes less lever pull to build the same pressure in the line.

As another aside, I swapped the stock MC from my '02 Superhawk (I had upgraded that to a 954 MC) and the same result: Hugely improved feel at the lever, much less pull, and much more immediate brake response. I still need to do an upgraded SS line and get some better pads put on, but just swapping the MC moved the front brake up to 'satisfactory' from deep in 'full-on sketchitude' territory.

I have to push it so hard to stop the bike..

krolinked
January 11th, 2013, 11:24 PM
I have to push it so hard to stop the bike..

I had this exact problem when I put on an R6 Cylinder. Any suggestions?

Its Unbelievably hard to pull that lever!

rojoracing53
January 11th, 2013, 11:43 PM
I had this exact problem when I put on an R6 Cylinder. Any suggestions?

Its Unbelievably hard to pull that lever!

You guys are install master with a piston that's to big for your desired feel. If the master is designed to push 8 prisons 4 on each side and you refuse it to 4 its twice as hard to pull the lever(more solid feel) if you reduce it to two pistons with the stock ninja caliper then its 4 times harder to pull. It gets harder to pull because you loseing your leverage against the caliper pistons. It's a balancing act with no right answer only preferences and opinions. If your only going to run a single caliper then get a higher quality master designed for use with a single caliper like on the ktm supermotos or the brembo 15rcs I just mounted on my bike.

Take a look here at what I've tried. The thread has fallen behind of where I'm at but I'm planning on updating it this weekend. http://www.ninjette.org/forums/showthread.php?p=617484

Mohawk
August 26th, 2018, 02:59 PM
The most important thing is the M/C to pistons ratio. For a twin 4pot brake system the best power ratio is around 33/1. When you reduce this to a single 2 piston calliper, then the sweet spot ratio is around 8.5/1. A lower first number will make the lever feel stiffer & require MORE pull by your fingers for any given brake effect. A bigger first number will make the lever feel softer, but will result in an increased brake effect for less pull by your fingers, but a longer lever travel.

To work it out do the following.
Piston diameter divided by 2, times the answer, times 3.14 will give you the area of ONE piston be it brake or master cylinder.

So the stock Ninja front calliper has 2x27mm pistons & IIRC a 14mm M/C.
So calliper = 27/2=13.5, so 13.5x13.5x3.14 = 572.3mm2, as there are two pistons, we double this number (x2) to 1144.6mm2. This is the total piston area.

The M/C is 14/2 = 7, 7x7x3.14 = 154mm2. So if we devide the piston area by the M/C area we get a brake ratio of 7.43/1 which is on the stiff side of optimal.

Say we changed to a 12.7mm M/C then 1144.6 / 126= 9.04, which is on the soft side of optimal, but will produce a nicer feel & a more easily modulated brake.

So optimal woul be a 13mm M/C if you can find one.

YMMV

DannoXYZ
August 27th, 2018, 11:30 AM
The most important thing is the M/C to pistons ratio. For a twin 4pot brake system the best power ratio is around 33/1. When you reduce this to a single 2 piston calliper, then the sweet spot ratio is around 8.5/1. A lower first number will make the lever feel stiffer & require MORE pull by your fingers for any given brake effect. A bigger first number will make the lever feel softer, but will result in an increased brake effect for less pull by your fingers, but a longer lever travel.
Exactly, that's more pulling force as in you have to squeeze brakes harder for same braking force. You trade off lever-travel for squeezing-force. With more leverage ratio, you need less squeezing/lever-force with more travel. With less leverage-ratio, you need more squeeze/lever-force with less travel.

Yup, surface-area = (r^2)*Pi