What would a 11/16'' master feel like with a single disc

[CalsXS2]

I'm not quit ready to do my dual disc yet. But The only master that I have is a 11/16'' for a dual disc. That is roughly 17mm I think. Can I run that with a single disc.

Could I get by with that for awhile. What would the lever feel like. Really bad as in should not even try it,,,,lol.

 

[angus67]

my 11mm mc is perfect for front brake on my chopped up 1980. Not wooden, but will grab if you yank on it.
I think 17mm would mushy. it would feel like air in the line.

 

[gggGary]

without being sure which caliper you have it's hard to tell http://www.vintagebrake.com/mastercylinder.htm

is the bible for such conjectures.

I'll guess it won't be much worse than sawing away at a drum brake hoping the bike will stop some time in the near future!

 

[CalsXS2]

without being sure which caliper you have it's hard to tell http://www.vintagebrake.com/mastercylinder.htm

is the bible for such conjectures.

I'll guess it won't be much worse than sawing away at a drum brake hoping the bike will stop some time in the near future!

It's on the 73 TX750. Same caliper as the early 650.

Right now I have no front brake. I'm ridin it like a bobber. And I don't like it. I am just putting around town. Now I'd like to go on a "RIDE". I aint interested in doin that with just a rear,,,,lol.

I guess I can try it just to see how it is. It will have to do for now until I get back in that gear. I gotta buy Goldwing tires dammit.

 

[CalsXS2]

So what diameter pistons do my calipers have??

 

[gggGary]

48mm


So using the bake chart he sez about 13 to 14mm MC for 2) 48mm opposed pucks

14 mm = 153 mm2
17mm = 226 mm2
or 50% more area than the high side of optimum. It'll work, it just won't feel "elegant"

Got the diameter from this ad:
HVC Reproduction Caliper Pistons are now available.
Made from stainless steel so they will never pit and rust around the seals again
48mm x 17.15mm
If you are not satisfied with our pistons we will offer a full refund.
Highest quality with the best price.
MADE IN THE USA!!
Found on various Yamaha models from 1971 to 1978
RD250 1975 F

RD350 1973-1975 F
RD400 1976-1978 F/R
TX500 1973-1974
TX650 1973-1974
TX750 1973-1974
XS2 Disc Brake
XS500 1975
XS650 1975- 1976
TZ250 76,77,78,81,82,96
TZ350 1976-1977
TZ750 1974

 

[XSLeo]

The stock master cylinder on the early two piston caliper was a 16 mm bore. The one marked 11/16 is about the same. The fell and power would be about like the stock set up. Not all that great. A 14 mm with one of the early calipers will work better.
I think the early pistons are 48 mm. The pads are 48 mm in diameter and the piston is very close to the same size.
If so the Vintage brake chart lists for two active pistons a 13 or 14 mm master is about right.
So a later 14 mm from a 77-80 or so standard would be fine.
I bought a Brand new 14 mm master off Ebay. It was sold as a replacement for an XS400 as well as a few others. It looks to be very close to the stock masters. Close enough so a stock lever fits it. You can't use the stock return spring.
The finish isn't quite as nice as stock but very close. The even come with a spare rebuild kit. $29 + S&H.
It works very well on my 75 with the later single piston dual disc set up. It should do fine with one dual piston caliper.
If you want, calling Michael Morse at vintage brake or 650central and chatting about brakes might help you decide.
Leo

 

[gggGary]

Anyone got pad advice for the early brakes? The 73 all stock, except brand X? pads, works better than I thought it would, but; I like your idea Leo, um Chinese ebay brakes, what could go wrong? But seriously I wonder about keeping that early brake switch with that MC.

 

[CalsXS2]

This is just for a temporary get it going type thing.

I have a 11/16'' dual disc master off a 78 Goldwing that I was going to use for my dual disc. Now the dual disc is on hold. I just need something on there so I can ride it a little more safely than just a rear,,,,lol.