Aftermarket bar mount brake master cyl question

recently ive been shopping around for bar mount master cylinders. ive got dual calipers up front and i know its recommended to use the 16mm bore master instead of the 12.7. i already understand that the larger bore is designed to be able to move more fluid to accommodate for the dual calipers. what i wanted to know is if anyone has tried the 12.7 on duals and how it performed or is it even safe to try?

the market is huge for 12.7 master cyls but slim on the 16's

 

42 views and nobody has an opinion?

 

I just bought an aftermarket bar mount off ebay. It's a 14mm and claims to be a direct replacement for my xj750. It should be here in a couple days and hopefully on my bike this weekend. I will let you know how it works out.

Item:
FR BRAKE MASTER CYLINDER YAMAHA MAXIM XJ700 XJ750 XS750

Seller:
usa-motorcycles-inc

It seems this is a standard item for this seller.

 

deff let me know, thanks man!

it looks very similar to the universal masters that "PartsNMore" sells.

 

that 14mm mc from e-bay will work fine if you have good lines if you have the original rubber lines a mc from a peterbuilt won't help

 

Got the M/C mounted yesterday. Had to do some modification on the stock controls by cutting off the lever mount. Now all I have to do is order a brake line for between the new M/C and the distribution block. Once everything is hooked up I will try to get some pics and a report up.

 

I'm thinking about getting one from a 4-wheeler. They have dual front brakes, so they should work with the dual brakes on my Seca. I'm going to get steel brake lines custom made also and get rid of the rubber expanding lines.
I'm assuming the one from a single disk brake will not send enough fluid to the calipers (small bore) to get the job done and will be dangerous.
I hate the cable activated setup from the factory. Not only for the fact that it's not very effective, but the access to the master cylinder is a mess to get at. It's a poor attempt just to clean up the handlebars in my opinion. What's wrong with a handlebar mounted master cylinder anyway. Looks alright to me.

 

The one I bought off e-bay was a pretty good deal I thought. It's pretty solid but I won't officially know the quality till I get some brake fluid through it. I bought mine directly from the guy but one went on auction for $56 last week....pretty awesome deal for brand new (hopefully it doesn't turn out to be a piece of crap).

 

Any news or experiences on this MC? I'm looking to get one for my bike as well...

 

I guess I'd shy away from those cheap new ones sold on Ebay. We're talking brakes here! Taking your life in your own hands?
I guess I'd rather buy something that has been proven instead of some cheap one I know nothing about. Just sayin'.
Maybe the new ones off Ebay are good too, who knows? Keep us posted.

 

Waiting on a brake line to connect the M/C. I was a little unsure also, but after looking how many similar products have been sold with no negative feedback, I was reassured. We will see tho...should know pretty easily whether its crap or quality.

 

Fender,
Just wondering also, they don't state if the master cylinders (on Ebay) are for single or dual disc brakes, so that's another reason I wasn't interested.

 

They do say it is a replacement for an XJ750 and it has a 14mm bore. Those two factors considered....should work with dual discs.

 

Yup, then it should work for ya.

 

Maybe they can't give negative feedback because they're all dead from faulty brakes! 8O
Just kidding. :wink: :wink:

 

That's a thought! Ya just never know.

 

Contrary to popular belief, the smaller the master cylinder bore the greater the bite is at the calipers.

 

As long as the lever doesn't come all the way back to the bars 8O

I tried a 14mm on my old 750 Seca (twin disc) and it wasn't big enough. Had to go to a 16mm unit.

 

Any updates on the quality of the MC?

 

Not yet....been very busy the last couple weeks.....hoping to get it done this week. As soon as it is I will post pics and review.

 

FINALY found some time to work on the bike. After ordering some parts from chacal (thanks Len for all the help) I installed the new master cylinder. Everything feels solid, just have to work a little air out of the system but so far very impressed. Once it warms up a little more here in Mass I will take it for a test spin. Gonna get some pics up this week to share with everyone.

 

Updates? !!!

 

And the further the travel of the lever.

Not news to me, but I am glad I understand hydraulics and the archimedes principle.

Don't go larger in piston diameter. Anything the same size that you can fit to the bars will work.

Can't offer much real world advice past that as I run YZF R1 brakes on Pumba.

 

Can you provide any experiences with the MC you're currently using, or alternatives from other bikes that you may know of? I really want to swap the wire/pump MC of my Seca with a bar mounted MC...

 

Sure just find one from a (dual disc) XJ650R (650 Seca.) Dual discs, bars with a "normal" angle to them, bar mounted M/C.

 

The problem with the 750 Seca is the right side control switch.......it's rather large, and thus fitting a "regular" XJ flat-reservior master cylinder creates interference between the hand lever and the control switch housing......you can't fully "close" the hand lever, the back edge of the lever hits (and stops) against the front face of the control switch before the hand lever can fully actuate the m/c piston (thus, you can't achieve full brake pressure).

Add to the problem is that the 750 Seca handlebars have these welded "tabs" on them used to secure the handlebar padding, which limits the side-to-side placement of the master cylinder...........of course, those tabs could be removed (hack-sawed and then ground off smooth). but then you lose the ability to (easily) mount the handlebar vinyl covers/pads.

It's a great unsolved mystery for us.....we haven't been able to find a hand lever that has the proper clearance, or a master cylinder with the proper offset (where the hand lever would mount and pivot from) to clear the original control switch. Other control switches (which are "skinnier") than the original might work, but then it won't match the look of the other (left) control switch, and the right control switch also controls the aux. light on these models, so there has to be that provision in the wiring and switch.

The one hand lever we found that did work (could be fully closed without interfering with the control switch) is shaped in such a way that it would require an enormous hand to be able to reach out and grab the hand lever while in the "open" position; it's too far away from the handlebars (in order to clear the control switch) to be of safe use for anyone without gorilla-sized mitts.......

And, the plastic wire harness connectors that are used on the original control switch are a unique beast, used nowhere else on the bike and not available aftermarket...........so even if you do find another control switch that will work, it won't plug into the stock harness, and you'll have to cut up the harness (or some other such remedy)......

I think Polock fashioned a solution that involves modifying the original right control switch housing by cutting off the hand lever monting bracket, and then filling in the hole and re-painting, etc., but tha's a somewhat involved process, and I'm still not sure how he solved the hand lever interference problem (the interference occurs at the left front corner of the rather-enormous control switch housing).

I know all this sounds like gibberish to non-750 Seca owners (and, maybe to them, too!), but that's what our research shows. If anyone has some solutions that they have found that works, please let me know!

 

there are some pictures in my gallery that kind of show it, trouble is i don't know what that MC is from. the switch is still unpainted in the picture, the silver is where the lever perch used to be. with stainless lines the lever can't come back far enough to hit the switch housing, their two finger brakes now.
i'll compare the seca MC to my sv and measure some stuff maybe that could be a clue

 

Thanks for your write-up Len.
I will be making a copy of the wire harness. It's been acting up after prolonged exposure to rain.
Since the winter is so long up here, I have until April to tinker.
Basically, I can buy a full set of aftermarket left and right controls...

 

My R1 master is 14mm so it may not work with the Seca calipers. I'm using the R1 calipers that match.

But have you looked at the thread here;
http://xjbikes.com/Forums/viewtopic/t=2 ... rt=30.html

 

I'm running an R6 MC on stock binders and it/they work great.
Throttle/switch/mirror mount from a 750 max to accommodate. All the wires are there but in different locations on the plug end(s)
throttle tubes are not interchangeable without some whittling btw

 

Ok... So, I got a little update here since it takes Fender512 forever

This one from Mikes-XS has an adjusting screw that crashes with your RH switches:

http://www.mikesxs.net/product/08-0255.html