R6 MASTER CYLINDER CONVERSION

[monkeywrench]

The brake switches may need modified depending on the type of master. Some use the two prongs you plug spade connectors on, alot of the GSXR use a connector that plugs in.

The bigger the piston, the more the line pressure which equates to a firmer lever. Every modern day sportbike has dual 4 piston calipers at a minimum so any of them will easily handle the single Buell caliper. If you want a nice(and cheap) RADIAL master get you one off a BMW S1000RR...

 

[user_deleted]

HOLD ON a second here guys. i am NOT criticizing anyone posting on this topic nor have i done this conversion mod...but front braking info is not only critical but crucial that it be accurate to avoid emergency room visits. keep these facts in mind when modding any bike brake system....particularly the front system which if used correctly does most or all your typical street bike braking.
1.master cylinders generate hydraulic pressure...it's called hydraulic advantage
2. if you move the cylinder piston say 15mm, you move approx. 5mm of fluid. the fluid pushing against the bottoms of the caliper pistons only has to move them approx. 0.5mm in distance. THIS is how the hydraulic advantage or pressure is generated.
3.when you increase the size(bore diameter) of the master cylinder you decrease braking power if everything else in your braking system remains the same. how? you are decreasing the hydraulic advantage. you will now have to squeeze the lever considerably harder than with your smaller stock master cylinder.
3. increasing master cylinder bore size means you move more fluid with with the same amount piston travel or lever pull distance than before. this always results in what i call a lever with a "wooden feel" and very very disconcerting to use. by that i mean a small amount of lever pull does virtually nothing....then just a bit more can lock the brakes. a brake lever should feel progressive in usage....NOT like a light-switch. increasing bore size typically turns the lever into an on/off light switch.
i mention this guys as the factory engineers carefully choose and match components so that lever/pedal feel is strong and consistent and predictable. all this based on components used in the braking system. i am not advocating no mods....i am advocating that you consider brake mods carefully and know what you're doing when performing them.

 

[oh9bolt]

[up]^

 

[rchuff]

I'm with John on master cylinder mods. I know the ones that came on our bikes work great so why change them plus going with a bigger bore will decrease the advantage. I would never mess with a major component of the braking system. Once again that is my 2 cents do what YOU like.

 

[Cooter]

It's not as simple as yes/no, right/wrong. This is why almost every system on a motorcycle is adjustable. Things like lever position, shifter position, etc…

It is very common, to 'adjust' your brake feel in a race car by moving the pedal pivot (for mechanical advantage), and especially the M/C bore size (for feel). Conversely, a larger caliper bore size (total of all pistons) increases hydraulic advantage and pad pressure.

Does Buell use a different M/C with the 8 piston calipers?? Or did they use the standard one because it's close enough? I dunno, but I think it's the same?

What Lunatic said is correct on how to calculate caliper pressure. A cheap 2000psi gauge that threads into your bleeder will test EXACTLY what you're getting before and after a change is made. It's also a great tool to loan your friends;p

I also agree with Lunatic that you shouldn't go changing things all willie-nillie. Any major changes to your brake system should be tested thoroughly before you put it on the street, but with some basic research it is an easy mod on a simple system to match how you like your bike brakes to feel. i.e. if you like a soft, progressive feel then use a slightly smaller M/C bore size. If you have Hulk hands like me, then use a larger bore size for a harder lever with less travel. Personally it lets me cover the lever with 2 fingers and not squish the rest of my hand on hard braking without moving the lever way forward.

Sorry for the long post

 

[BuellRonin]

Wow. I never considered the implications of something going wrong. But I think I asked about the bore size on another post and got no reply.

I did the mod a week ago and after testing on some straight stretches of road I felt it was working properly.

I must say, I do feel that the MC mod fits my expectations of what I want my brake lever to be. I don't have monster hands like Cooter, but my grip is pretty good on it's own.

With my Nissin, it felt quite squishy, with a longer pull until it engaged. Now with the Brembo, I still have a small distant of play before the brakes engage, but not nearly as much, and it feels stronger. I did look around on the topic and found no large amounts of failure, as long as you stayed within suggested MC's.

I appreciate all the concern the veterans show on this forum and continue to look for vital info on any major mods such as the brake MC mod.

Much thanks for all who support on this fourm.

Cheers!

 

[fbfrider]

All great posts! Lunatic and cooter made some great point about safety and doing your research first before changing something that has been properly engineered. This mod is not for everyone and in fact the Buell master cylinder works just fine. My decision to change the master cylinder came from research and experience. I was looking for a more refined feel that was firmer and that would offer confident feel. The new 1190RX is a good example, which uses the same brake caliper as my 09 XB12s and a very similar master cylinder to the one I am now using. On the flip side, there is over kill which is best explained as being like an on/off switch. Good example, putting an RC51 master cylinder on a CRF450 supermoto. Yes, I've seen it done and rode it on a track; bad idea! The brakes had more bite than the motor and it wanted to endo every time your finger touched the lever. I'm all for mods if it makes sense and can inspire more confidence in your riding, but safety must come first; and ultimately taking a riders road course (track day if you will), is the best way to increase knowledge and skill. Thank you to all who weighted in on this post, I appreciate the feedback. FYI, I work at a dealership that sells Honda, Yamaha, Kawasaki, Suzuki and I love the fact that I ride a Buell!