Have you checked out a 400EX? They are almost the same as a 250R front master I think.

 

Nope, not yet, but these two above will substitute just fine. When I see a 400 I will check it out. The important thing is that 1/2 is stamped into the casting (meaning a 1/2" piston size) and that you like the look.

The CRF230/150 is so slim it looks awesome....

 

service honda and hondaparts direct, have you tried them? Looks like a CR230F front master cylinder complete on hondaparts direct was 81.00 and change, the rubber cover was 3 dollars and I didn't see how much the lever was.

Are you sure a small little master cylinder will work? This only has to clamp one brake caliper. I think I would go with the 400ex or 450r since it has to make two calipers work along with provide pressure for two brake lines.

I put 400 ex front brakes and spindles on my bro in law's 250r and used the 250r master cylinder (rebuilt) it didn't apply enough pressure with the huge single piston that the 400 ex uses. So the 400 ex master cylinder on the 250r brakes would probably be the ticket.

 

Nope..... Here is the thing. The master cylinder's piston is what matters, not the physical size of the reservoir or the lever, or anything else.

The 250R comes with a 1/2" piston (12.7mm) to work the OEM Honda dual piston calipers at each front wheel. Therefore an exact replacement would be any master cylinder with the same piston size, such as the TRX450R or CRF150/230 master cylinders, both of which are 1/2" pistons (12.7mm).

The 400EX has different brake calipers, and therefore requires a different master cylinder to appropriately push them outward to the brake rotors.

Just because you can fit it on the handlebars doesn't mean it will work right. There is a science to this.

The CR series bikes have 11mm pistons for instance. This smaller piston would offer super feel for the brakes, but would require a lot longer lever travel to lock the brakes up, due to the fact that the smaller piston pushes lesss fluid. Some sportbikes use a 19mm master cylinder piston. This would allow you to barely actuate the lever before the calipers lock onto the rotors, but would take away the lever feel needed to slow down properly, making the brakes have a "wooden" feel).

Because I am keeping the piston sizes the same everything will work exactly the same, just look a whole lot newer/better.

 

The piston size is the only thing that will affect the brake actuation/feel. .. you are correct, but keep in mind that the original 250R reservoir is bigger than the db reservoirs for a reason.

As your pads wear down, more fluid has to be in the calipers to push the pistons out further. With stock equipment, if you start with a full reservoir on new pads, you will still be fine when the pads wear out.

With the smaller dirtbike reservoirs, you may need to add fluid at some interval, and then when you put new pads on and compress the caliper pistons, you may overflow the smaller reservoir.

If you're cool with watching your fluid levels closely, the setup you've identified should work very well for you.

 

I put 400 ex front brakes and spindles on my bro in law's 250r and used the 250r master cylinder (rebuilt) it didn't apply enough pressure with the huge single piston that the 400 ex uses. So the 400 ex master cylinder on the 250r brakes would probably be the ticket.

was this with stock or aftermarket lines? those old lines will make a good system feel spongy.

 

New Updated Master Cylinder Available!!! ..?

seems as tho you are talking about "swapping in" a different machine's parts...that you fell will work good
& not actually updating any TRX250R pcs ...correct?

 

I'm running the ex calipers on a 250r master with braided brakes and they work good.almost as good as the dual r's. Good thread, got me thinking of doing some kinda mod to my rear.

 

Yes, it is a swap.

Turns out the new TRX400EX and TRX250EX both have the same front brake master cylinders as the TRX450R, all of which will work.

The CRF150/230 have to be "F" models, the other models will not work as they are 11mm.

Even with pads wearing down I have never seen fluid fall to even the middle of the sightglass, so I am going with the smaller reservoir to try out....

 

If the fluid does get low I don't plan to add, that is a bad idea on a closed loop system. If you add more then install new pads the pads will rub on the rotors.

Same thing happens with cars...

I get what ya mean though!!

 

If the fluid does get low I don't plan to add, that is a bad idea on a closed loop system. If you add more then install new pads the pads will rub on the rotors.

Same thing happens with cars...

I get what ya mean though!!

If you need to add to keep the cylinder from getting air in the lines, you need to do it... very likely not a problem, but something I would keep an eye on. I would just say that if you do add fluid, you need to drain it when installing new pads, that's all. .. probably not a big deal either way.

I agree that the dirtbike master cylinders are lighter and look cooler than the ones made for quads. .. if you go ahead, snap a couple pics and throw them on here.

 

If the fluid does get low I don't plan to add, that is a bad idea on a closed loop system. If you add more then install new pads the pads will rub on the rotors.

Same thing happens with cars...

I get what ya mean though!!

If you need to add to keep the cylinder from getting air in the lines, you need to do it... very likely not a problem, but something I would keep an eye on. I would just say that if you do add fluid, you need to drain it when installing new pads, that's all. .. probably not a big deal either way.

I agree that the dirtbike master cylinders are lighter and look cooler than the ones made for quads. .. if you go ahead, snap a couple pics and throw them on here.

 

if i recall a honda cbr600 street bike front master cylinder will work. i dont like the 400ex master cylinders they feel spongy even with new stainless brake lines.

 

if i recall a honda cbr600 street bike front master cylinder will work. i dont like the 400ex master cylinders they feel spongy even with new stainless brake lines.

yuppers but i believe it has to be from a 02 and back. cant be for sure though.

 

Got my 1/2" CRF150 master cylinder in last night. Will let you know how it goes and post pics. $25 on Ebay and it only needs a new lever!

 

The CRF150/CRF230 master cylinder was a bad idea, because it only gives 1/2" clearance from the bars, not enough for a thumb throttle.

If someone is running a twist throttle and wants this I will sell it for the $25 I paid plus shipping...

Now looking for a TRX450R master cylinder. All the same features but a bit more clearance....

 

The CRF150/CRF230 master cylinder was a bad idea, because it only gives 1/2" clearance from the bars, not enough for a thumb throttle.

If someone is running a twist throttle and wants this I will sell it for the I paid plus shipping...

Now looking for a TRX450R master cylinder. All the same features but a bit more clearance....

I have a complete 400EX front master for sale.

 

I bought a TRX450R master cylinder instead. It has adjustable reach and looks brand new...

Thanks though!

 

I bought a TRX450R master cylinder instead. It has adjustable reach and looks brand new...

Thanks though!

Thats what I'm running. B)