Is this my stock MC for front brakes

[Suckerpunch]

The reason Im asking is because my local Yamaha dealer ordered the OEM rebuild kit for me and all The parts were double in size. After searching and searching, then double checking the order twice, the dealer said I must have the wrong MC on my bike.

Here are a couple pictures of the one mounted on the bike. Also on the bottom of this MC, It has print that looks to read "NISSIN 14"

The reason for this rebuild was originally due to spongy brakes. Ive bled and bled the brakes and I cant seem to get a stiff handle. I can stop my bike just fine but, I can also squeeze the lever all the way to the grip, I dont think that is normal. My guess is because of this small piston MC.

1980 XS1100 SG

[DGXSER]

That is decisively not the stock reservior or cover. But the layout at least of the MC looks stock.

[CatatonicBug]

That MC has an oblong window in it. All the XS/XJ MC's have round windows, IIRC. I would say that assembly is NOT the stock MC for ANY XS11.

[Montreux_Blue]

It kinda looks stock with some kind of billet cover and lid on it.

[Suckerpunch]

I didn't measure the piston when I had it removed but, it was maybe 3/8" wide at the widest point. It looked like the OEM one was close to 9/16 wide.

Im sure im wrong on both measurements but, it was that much of a difference.

Does the NISSIN 14 tell us anything?

[CatatonicBug]

Does the NISSIN 14 tell us anything?

I would say that means it's a Nissin brand Master Cylinder, with a 14mm diameter bore.

[Suckerpunch]

I would say that means it's a Nissin brand Master Cylinder, with a 14mm diameter bore.

ok,makes since. If this MC has a 14mm bore, what is the stock mm?

And does anybody have a stock MC they can part with?

[Montreux_Blue]

My stock one says "K 5 NISSIN 1 11/16" on the bottom of it.

[Geezer]

It's from a smaller single disk Yamaha and odds are no matter what you do with it, the brakes are going to be mushy. The piston is just too small... You can look for a good used one or a new one from Parts N' More...

Geezer

[fredintoon]

- - - the dealer said I must have the wrong MC on my bike. - - - on the bottom of this MC, It has print that looks to read "NISSIN 14"
The reason for this rebuild was originally due to spongy brakes. - - -

Hi 'punch,
the stock m/c is also a Nissin but it's bore is 11/16".
If your orphan Nissin has an 14mm bore (which is slightly less than 9/16") that would give the exact symptoms you describe.

[BigRed]

And now for something completely different....

Stainless brake lines are supposed to firm up your brake lever. I can also pull mine to the grip. I don't know if my MC is stock or not. My brakes can stop me as hard as I am willing to try, but I also don't like that I can max out the lever so easily. I plan to upgrade to stainless lines; then you lose the stretch of the rubber lines, and the brakes should be less spongy.

[CatatonicBug]

Stainless brake lines are supposed to firm up your brake lever. I can also pull mine to the grip. I don't know if my MC is stock or not. My brakes can stop me as hard as I am willing to try, but I also don't like that I can max out the lever so easily. I plan to upgrade to stainless lines; then you lose the stretch of the rubber lines, and the brakes should be less spongy.

It may be that your brakes have some air in them too. Have you tried re-bleeding them?

[Suckerpunch]

yes, Im sure all the air is out.

Looks I just need to locate the correct MC. I do stop well but, would like the brakes to work properly for my safety.

It may be that your brakes have some air in them too. Have you tried re-bleeding them?

[CatatonicBug]

yes, Im sure all the air is out.

Looks I just need to locate the correct MC. I do stop well but, would like the brakes to work properly for my safety.

Yeah - yours is because the bore is too small. It's Big Red that may have air in the lines.