Better master cylinder?

[pdxjim]

What's the best master cylinder upgrade for RD350B stock caliper?

What size is stock?  What size is best?  Is smaller better?

What modern(ish) master cylinder (that I can get off ebay), that has a two piece mx style perch (because we may crash and don't wanna have to take the grip off to replace it) works the best?

Please don't make me explain whey we are using a stock caliper but a modern master cylinder ... it's a long story.

[retaRD]

There's a couple ways to go with this..
Kawitriplefreak Jim and Frank B run Yamaha Zuma masters with single FZ1 silver/blue dot calipers.  Point is it comes down to surface area of the caliper pistons to master cylinder ratio.

Have you looked at the table on vintage brake?  It's a gem.  I've not used an aftermarket master with the stock caliper but I know it sucks, to the point where the stock master could push two stock calipers.

Like a block of wood.

If you "math out" the stock caliper pistons to what's on Vintage brakes' chart you'll know what master you need, then it's a matter of scouring eBay for one that falls in the range. 

http://vintagebrake.com/mastercylinder.htm

[m in sc]

i like a 14mm with a stock caliper. just my preference.

stock size is 5/8" (16mm!)

[dugsgms]

I used this 13mm one from MikesXS. Works great, more stopping power and better lever feel.
https://www.mikesxs.net/yamaha-xs650-1mh-master-cyl-assembly-13mm-bore.html

[pdxjim]

I used this 13mm one from MikesXS. Works great, more stopping power and better lever feel.
https://www.mikesxs.net/yamaha-xs650-1mh-master-cyl-assembly-13mm-bore.html

That looks pretty good, but I'd prefer something a bit more modern.

Ideally off a modern(ish) dirtbike, raw aluminum, small reservoir, no mirror mount.

With a matching clutch perch!

Who's got a link for me?

[pdxjim]

https://www.economycycle.com/shop/yamaha-rd250350400r5ds6ds7-parts/frame-related/brakes/front-master-cylinder-kit-magura/

Anyone running this one?  Is it better than it looks in the pics?

Coz the pic makes it look hella cheap.

[SUPERTUNE]

I use 2015-up SR400 Yamaha. 14mm.
Have to buy all la carte though from Yamaha and will be about $125 and is just like the one posted on the Mikes XS 13mm.
I don't have any more modern setups.
Chuck

[SUPERTUNE]

Those work good too.
But no lever height adjustments, fixed.
C

[idr5c]

The 14mm Brembo RCS looks nice 


https://www.kurveygirl.com/shop/product_info.php?cPath=170_174&products_id=796

[dugsgms]

As does this one from braking
https://www.amazon.com/Braking-Radial-Clutch-Master-Cylinder/dp/B00M9LWOAW

[pdxjim]

Both of those are way too fancy for this project.

I just need a good solid OEM master off something newer than 1975.


Ordered the MikesXS one.  It'll do and we have an extra lever to fit for a race spare.


For the future .. a chart of which bikes run what size master cyls would be super helpful.

Someone get on that, OK?

[m in sc]

ex500 is 1/2" im pretty sure, ive used those before . just fyi.

[pdxjim]

Yep.  I put an ex300 master on my TDR.

12.7mm or 1/2".

[RDryan]

This is an interesting thread as it rehashes my master cylinder woes. I have nothing to add and I don't want to hijack it but I must relate that I bought one of those 60 dollar OEM style replacements that's made in China and comes with the brake lever. Both HVC and Economy Cycle sell these. They're beautiful and have nice feel at the lever even with the stock brake lines and calipers. For the money they're hard to beat except for one huge issue. Well the reason I replaced mine was because although I tried to replace the rubber seal thingy inside it and no matter how much I tightened it or added plumbers tape to the cap threads the silly thing would leak. So wouldn't you know it the same thing started happening with this other new replacement one. I'm starting to think that the threads are crude on these things and the rubber seals don't do a good job of keeping the brake fluid where it belongs. Not sure why you guys don't go with these style master cylinders except to say if it's because they wanna leak then that makes sense.

[sav0r]

I think it's because used Ninja master cylinders are a dime a dozen, the correct size, and are known to be reliable. That's what I used on my bike as well.