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Discussion Starter · #1 ·
I was wondering if there was a possibility for me to replace my right handbrake assembly and replace it with another bike's assembly to be able to remove the twofiddys box fluid reservoir and replace it with a cylinder from a big bike? Would there be some work that needs to be done in regards to making hoses fit or something needs to be done with the Master Cylinder? I am new to motorcycle fabrication or work in general and so I would appreciate the help.

I have a 2011 CBR250r streetfighter bike.
 

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You should be able to replace it with one from another bike. Keep close attention to the bore size. You want to replace it with one of the same size. Google is your friend in this case. Find out what yours is and then work from there. Once you find some that are the same size, try to get one with the banjo bolt in the same general direction to be able to reuse your existing brake lines.

...and show us pictures of your ride!
 

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Discussion Starter · #3 ·
Okay, So I checked the bore size of my cbr and it said it was 76mm? Does that seem correct? What exactly does the bore or the size mean? Do you know what bikes might have the same size off the bat? I am using google current but was wondering if you knew of any specifics with that size. Thanks.

I will! I just need to get some pictures of it, I live in a residence halls on campus so it is sort of a treck just to get to the garage haha.
 

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Discussion Starter · #4 ·
So I made some progress and I found a guy parting out a 2012 cbr 1000rr Hrc that might be able to get me a brake assembly. It has the same bore size as my bike. Does that mean it would just be a simple swap and bolt job? Sorry for all the questions. But I do appreciate the help.
 

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The friendly Ghost.
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I went looking for brake masters on Ebay that fit CBR250Rs. These are what I found:

(Look for the an 11, 12, 1/2, 14, 5/8... they are usually circled.)



http://www.ebay.com/itm/2012-2013-H...Parts_Accessories&hash=item35dab17ac1&vxp=mtr

This appears to be an 11 mm bore.



http://www.ebay.com/itm/11-12-13-CB...Parts_Accessories&hash=item3f3ca7c6ed&vxp=mtr

This one as well.

I am unsure what the stamped 76 or 79 are, but they don't make sense as far as bore size goes.

There aren't many 11mm masters that I have seen out there and increasing to a 12 mm or 1/2" bore size will make your brakes activate quicker and be harder to modulate. Yes, it will work, but I personally would suggest against it.

The higher CC CBR brakes won't work, they have considerably larger caliper piston areas and require an increased amount of fluid to get the same brake feel. The CBR1000 master cylinder will cause your brakes to feel wooden and easy as hell to lock up.
 

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Flanman, please educate yourself on master cylinders and bore sizing before tackling this project, it'll benefit you in the long run. The 76mm bore size you mentioned, sounds like your engine, not your brakes. Casper's number of 11mm sounds right since the CBR250 likely has single piston sliding calipers, or something close to that.

Have a read: http://www.customfighters.com/forums/showthread.php?t=56704
 

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Old, bold rider
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Having worked on motorcycle disc brakes for as long as they have been fitted by the factories, and the original magnesium Lockheed double acting units (that's over 40 years now) I have a pretty good handle on things. You can swap from another bike as long as you get the master cylinder bore size right. Here's a post I wrote a short time ago that outlines the procedure for fitting a radial master cylinder to a system using an axial MC originally including a spreadsheet to get close to what you need, but will also work to fit a different axial to get the feel you want: http://www.customfighters.com/forums/showthread.php?t=92954
As it states, too large a bore, such as a MC for a bike with dual front calipers, and the brake will take way too much effort at the lever to stop, and too small will get touchy and mushy at the same time, making holding the brakes just this side of locking very difficult.

Without the specifics of the bore sizes of the caliper and MC I can't give you any specific advice, but with a quick visit to a Honda dealership to get the pertinent dimensions from a service manual you will be armed with the necessary information to make a swap that will work for you.

Good luck!

Rob
 

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The CBR250 has indeed an 11mm master cylinder, same as my MSX125, but also the CBR500.

The brakes on my MSX are truly brilliant, with absolutely perfect 'feel'. Although I admit it's slower and lighter than the 250 which would help, the 250 has a significantly bigger disc which should balance things out.

I keep looking at big brake conversion kits, but can't quite bring myself to do it, since the stock parts are just so good... even if a bit vanilla to look at.

If you really want it, then you could look into brembo conversion kits intended for an MSX and get matching brake caliper and master cylinder. If the MSX and CBR caliper part numbers are identical then any conversion kit should also work (right?).

http://www.hondagrom.net/forums/61-motobot-racing/5475-grombot-virus-s1-catalog.html

Order from Thailand and you can get a 4pot brembo bracket for as little as $11 (see page 67 of the catalog linked). Once you get the bracket, you 'should' be able to fit the whole front brake from a 600 monster. I did this on an old CB-1, and trust me, it is absolutely enough brakes for a small bike!



Proviso - I had to 'massage' the CB-1 switchgear to fit the brembo master cylinder. You might be better off fitting a 1/2" nissin master cylinder from eg. a Hawk GT (with mirror mount) or VFR800 (if you don't need a mirror mount).
 
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