replacement master cylinder?

http://www.ebay.com/itm/280992571598?it ... m=&vxp=mtr

im looking at this to replace my current master cylinder because it needs rebuilt and the sight glass is totally gone. and knowledge if the stock lines will fit it? and if it will fit my stock bars? thanks guys

 

I believe the xj650 uses a 16 mm bore and that is a 12.7. Which as was explained to me may not give you enough force to stop properly. chacal sells the kits for the same price plus sight glass. and I understand their parts are top notch. not that Chinese b.s.

 

i put one like this from this same place on a seca a few years ago still works fine
ebay
the 14mm bore was smaller than original but it works fine with dual disks, should work with single.
if you look at the ones he has, there all basically the same. just find one with the banjo bolt in the same place and the angle right.
10x1.25 is the size banjo bolt you want.
you want new brake line too, believe me

 

Explain to me why people here feel brake hoses are only good for 4 years or so. I believe I read that a time or two here so wonder just who here has had a brake failure with a hose due to age and how old was it.

 

don't know of any failure but after i replaced mine the brakes went from a 3 to a 8 out of 10. the only reason they got a 3 was that they didn't leak.
the hose might never really blow out but they get soft and then no matter how hard you pull the lever the fluid can only transfer pressure to the wheel cylinder until the hose swells, any more pressure just swells the hose more.
it can make you get religion real quick

 

Yeah my lines are from October of 80
So new lines it is. And I'm glad it worked good. I'm ordering it. U can't beat the price. I can't even rebuild my oem one for what they want for complete.

 

http://www.xj4ever.com/choosing%20a%20sight%20glass.pdf

 

I believe it is the inverse of that actually. Since the area is smaller (and pressure=force/area) it will actually require LESS force input from the user via the brake lever to develop the requisite pressure for braking.

So the only problem I can see is that you can now OVER-pressurize your rubber brake lines beyond their design capabilities, leading to a greater likelihood of sudden failure.

Long story short: GET THE STEEL BRAIDED LINES and you can buy aftermarket (and yes, avoid chinese crap whenever possible and buy from chacal)

 

I should add that, with the smaller bore piston, your stroke (the distance the piston must travel) should increase (since work=force*distance, if you decrease force, you must increase distance to provided the same braking 'work')

Anyone feel like verifying/debunking my physics!?

Based on this, you may have a longer lever pull (unless the aftermarket unit is designed to provide a longer stroke with a given lever pull)

 

okay so the yamaha mc i have says 1/2 im assuming this is the bore size as its on the outside of the bore. 1/2 " converts to 12.7 mm wich is the size of that mc. so i went ahead and ordered it. also the banjo bolt size is correct too. and the angle appears to be the same. ill letchall know if all goes well. now lets just hope i can win my intakes for a reasonable price.

 

When I did my rebuild last winter I installed stainless lines, even though the rubber lines were only 6 years old.

Cut my emergency braking distance @ 40mph by 2/3

 

BECAUSE YAMAHA SAID THEY HAD A FOUR-YEAR LIFE SPAN. So thirty years is well past any "designed in" margin of safety.

I have had an 8 or 9-year old Japanese brake line pop on me, it's not an experience you want to repeat.

The problem is not the outer, rubber hose. It's the "nylon" inner liner; they deteriorate over time soaking in brake fluid and begin to crack or split. Once that happens, the hose begins "ballooning" and you get really spongy brakes--- until it POPS. Then you got NO brakes.

If Yamaha said 4 years, then I tend to think replacement after 30 years is just being PRUDENT.

In addition to the fact that stainless lines are a vast improvement over even brand new stock rubber ones.

 

Yeah 30 years is old but I think 4 years is just yamaha telling us to spend money.

Btw I can get 3 stainless custom made lines for about $65 from an outfit out of canada on ebay and you can get them in either silver or black. Comes with new crush washers too. I am not sure but I think that would be cheaper than OEM rubber lines.

 

Hey guys! got my new MC all is well. it appears to be the same size in every way except for the resivor. just a tick smaller. also the sight glass is actual glass and for the money shipped i think it was 43 buxs. you cant beat it! just have to modify the original break light wiring like talked about but wont be hard at all! ill check back in once i get my replacement lines and caliper rebuild kit all together and everything hooked up mini vac'd n bled. but so far im verry pleased. waiting on my carb kits and other carb parts. whoot!