Can anyone explain the same of driving a small caliper with a larger master cylinder? Stock brakes on my Ninja 300 have a stutter in the lever as pressure starts to build. (I've felt this same thing on the two other 300s I've ridden). I'm not sure if it's in the MC or in the ABS, so I was thinking of fitting a Nisjin R1 master on to test. The internet advised against driving that small single caliper with the larger 18 (or 19?) mm bore of the R1 master. My question is why? What's the danger of pushing more fluid? Brakes that are TOO touchy? Would it blow out the calipers? Sent from my Pixel 3 using Tapatalk
Is this a chatter feedback, or a "step" in the lever progression? Like the lever hangs up at a fixed point, or you get a series of vibrations in the lever?
There are a lot of factors on choosing the right brake master, number of caliper pistons(and are they opposing?), the size of the caliper pistons, the size of master cylinder piston and the fulcrum distance of the brake lever. The danger might be that you won't be able to stop the bike, the hydraulic ratio will be so far off that you won't have enough leverage to squeeze the brake lever enough to produce the same pressure.
Not feedback. The chatter is present at standstill. After the pre-travel, right it starts to build pressure, 'a series of vibrations' is a good way to put. Think of windshield wipers chattering across a dry windshield, but felt in the hand. Feels like friction in the system - like I'm pushing a dry o-ring through the cylinder. Of course, I've already greased the pivot pin to eliminate that variable. Sent from my Pixel 3 using Tapatalk
Not to my knowledge. Bought the bike end of season, haven't even had it on track yet. I'll reach out to the seller. Sent from my Pixel 3 using Tapatalk
I was thinking of ONE of those variables - the mechanical advantage I lose from the MC piston size, but failed to consider other variables, like distance to fulcrum. Thanks for pointing these out. I grasp the physics of all you described, but that begs a follow up: Is the loss of braking power the ONLY concern here? I'm happy to tinker with it and see how the power and feel compare (before I'm screaming into T1) as long as there's no danger of damaging components and causing a system failure Sent from my Pixel 3 using Tapatalk
Pull the ABS fuse. Then ride the bike see how it feels. I have the same bike... I see alot of folks riding stock ones at track days and I always ask how does the ABS feel? I might have asked them some benign question about the weather...lol
I wonder if you're feeling the floating caliper aligning to the rotor and sliding in place to take up slop?
I don't see how you could damage the system by using a master that would produce less pressure. If you look it up you should be able to find a master cylinder to caliper piston ratio calculator, you could use that to compare the stock system vs other options.
If it's like I think, it's a feeling of "chatter" in the lever travel, not brake vibration feedback; therefore:
Years ago, I tried a big master on a smaller caliper set up. I lost brake feel, and overall performance. Very little lever movement from no braking to when the lever stopped before lock up. Brake modulation was nearly impossible. It became an on/off switch. When I went back to the stock master, everything was better for the track. I went form an F3 master, designed to push 2 - two piston calipers, to a ZX7 master, designed to push 2 - six piston calipers.
What are the actual sizes of the master cylinder bores? The 300 could be 12mm-16mm. The R1 is probably 16mm or 18mm. Going from 13mm to 16mm won't be too bad. You'll lose a noticeable amount of feel, but I doubt you'll be unable to stop the bike. Going from 12mm to 18mm will probably be terrible, producing the symptoms that stickyboy274 said above.
I believe the OE ninja 250/300 master is a 1/2” bore and most OE 600/1000cc bikes are 5/8” bore. That’s what’s stamped on the masters anyways. Personally if I was upgrading master cylinder on a ninja 300 with a stock caliper I’d go for a 14mm bore. I tired a 15mm for one day last year and hated it. Switching back to OE master this year.
