Let's talk aftermarket Master Cylinders

Hey everyone,

As my project rolls on, I'm starting to think about my "cockpit" and how I'd like to clean it up. I'm going to do away with my Clutch safety switch (But keep the sidestand switch), place a choke lever on the carbs directly, place a headlight on/off on the headlight housing, and then place my keyed ignition, kill switch, and start button on the outside of my electronics tray.

Most importantly (and on topic) I would like to get new perches and levers, something sportier (And shorter) like the ASV's or potentially a knockoff.

I apologize if this has been covered before, but if I buy some sort of sportbike levers with a reservoir and master cylinder, do I HAVE to stay with a 16mm piston bore size? They're proving hard to find.

Something like these:



Pardon my ignorance, but I like the way these look and function. Most of them seem to have a 22mm piston bore. So am I out of luck? I don't have a problem buying a traditional flat mounted MC/reservoir/Lever combo, but I'd love to do something like the above.

If anyone has any insight, I'd love to hear it.

Thanks!

 

FRONT MASTER CYLINDERS:

mc1) OEM and aftermarket complete front and rear MASTER CYLINDERS, brand new units perfectly replace the originals. Contains lid, diaphram, piston assembly, and lead wires for fluid level switch (on models so equipped). Some master cylinders may NOT include the brake light switch, lever, or mounting hardware........please review the individual applications below for complete information. Lettering and information on the reservoir cover will differ in appearance from your original.

By the way, if you are considering upgrading from one size master cylinder (piston bore diameter) to another, here's the decision parameters that you'll want to consider:

http://www.airheart-brakes.com/pdfs/MasterCylinder_Selection.pdf

 

Thanks for the diagram. Guess I've got some homework to do.

If anyone has actually gone ahead and used a different MC size, could you please post the differences in braking? Thanks

 

http://www.vintagebrake.com/mastercylinder.htm
this might help

 

Larger m/c = less lever travel and feel, smaller is more lever travel and more feel

My Ducati Darmah and MHR both use the same calipers, the Darmah had a 15mm m/c and the MHR a 14mm m/c, MHR brakes were much nicer, more lever travel but easier to modulate

 

Well I'll be honest, I like the way my brakes feel now and when I upgrade to SS lines, I'll probably like them better. I need to replace the MC because I don't love the way it's tilted, for safety and cosmetic reasons.

I suppose I'll look for any sort of MC that deviates 2mm either way from 16mm, but at the end of the day its looking like I'll be staying with a 16mm or 5/8ths. Unfortunately, those fancy ASV's or sportbike styles don't come in those sizes. Ah well.

 

I know this is an old thread guys but here's a shameless bump so I don't need to start a new one. Even after reading the two linked articles I'm still a little confused. If going from a stock 16mm bore to a 17mm bore, will this increase travel and "feel" or will this make it go from no brake to locked up brakes?

It'd be cheaper for me to buy an aftermarket MC than it would be to rebuild the current set. Plus, it's missing hardware and looking ROUGH to say the least.

Thanks for any information.

 

Going to a larger bore master cylinder will result in less hydraulic pressure being developed at the brake caliper. Too big of a jump and you will not have useable brakes. I found that a 1mm increase was too much on a 650 Maxim. The bike always felt like there was air in the lines (mushy feel and little stopping power). Switching back to the stock bore size returned things to normal.

 

Thanks k-moe, were you using stainless brake lines or rubber?

 

A braided stainless line from the master directly to the caliper. This was a budget recommission; the bike came with a new braided line, so we kept it.

 

Duplicate

 

Duplicate

 

My favourite 'aftermarket' if you could call it that, was/are the XJ900 m/c sold off as NOS by the UK Yamaha importers for some reason. Perhaps they had an overstock supply. Anyway, they suited my Suzukis much better than the OEM m/c, because of a slightly different leverage and lever angle, as they were nominally the same bore (5/8th" or 16mm). I still use one of them, but I discovered that the Suzuki calipers, when a bit of wear and tear happened, caused a bit of lost motion in the system, but the master cylinder had enough reserve to cope with that.
On the XJ900F, the twin-opposed piston calipers are like night and day compared to the old GS - two-finger braking all day, every day; no wear, no lost motion and a really nice feel to the brakes all the time. The 5/8th bore size is ideally suited to the caliper piston total sizes in terms of hydraulic leverage.

As an illustration of the above points.
On the XS650, a total rebuild of the calipers still left me with slightly vague brakes. I fitted a Kwack Nissin 14mm and had superb braking power, but that old lost motion bugbear came back up again. Sod it - fitted a 16mm (5/8th") m/c from a Honda Deaville and never looked back. The Deauville m/c has a nice span-adjustable lever and it ergonomically suited to me.

 

Has anyone tried a "universal" m/c lever combo that can comment on it? The Chinese versions on ebay are so much cheaper and look 1000x better than the stock one and I need to upgrade but don't want to spend too much money!

 

People have tried them. You sometimes get less than you pay for.

 

I am a notorious tightwad and cheapskate. If there's a method of not giving dealers or parts sellers money when I can do just as well or better by re-sourcing something, I'll do that.
Brakes are something I cast a careful eye on - which is why I use good quality OEM parts from other bikes and, if necessary, rebuild Nissin master cylinders rather than trust my neck to some anonymous pot-metal from Shangzhow.
Your money, your neck, your choice.