brake component interchange and benefits?

CalAl

There's quite a bit about this on this forum already, but just to simplify:
What years XS1100 or XJ1100 rotors and calipers will fit my single disc '77 forks and wheel? The 1100 rotors are a bit thinner and slotted so they weigh a bit less? Are the 1100 calipers dual piston or in other ways better than the XS650?
Thanks
Alan

xsleo

The 1100 standards use the same calipers as the 650's. Mine came from a 79.
The 1100 specials use a smaller disc and different calipers

jetmechmarty

The last reply was incorrect. The XS1100 Special runs rotors or discs that are identical to those on the late XS650. The SG and SH have slots. Otherwise, there is no difference. The XS1100 standard has the same rotors and calipers as the late XS650. The "H" has the slotted rotors. They are not thinner than the XS650.

The XS1100 Special has calipers that are not applicable to the XS650 because it has leading axle forks.

I think the confusion comes in if you throw the XS750/850 into the mix. These bikes have smaller rotors not compatible with the XS650.

The bottom line is, if you have an XS1100 standard, the front brake system can be transplanted to the XS650. The XS1100 Special is the same except for the "Weird Harold" calipers.

AFAIK, the XJ1100 can donate rotors as well. Otherwise, it has a completely different brake system.

XS1100 standard (1978-1981)
XS1100S (1979-1981)
XJ1100 -1982 (except Canada)

650skull · Support Staff Joined: Jul 19, 2007 Posts: 1186

Not sure about the XS750's in the States, but here in AUS the front rotors off the XS750 are the same as the 650 rear discs. bolt strait on

grinder · Full Member Joined: Jul 29, 2009 Posts: 36

Do you need to change the master if you are adding a second disc? I have a 77 also.

jetmechmarty

If you add the second disc the master cylinder won't see a difference unless you also plumb in the second caliper. ;^) You can probably get away with using the same master cylinder, but it will not feel the same. I believe it will offer much less resistance. You may want a larger bore master cylinder.

grinder · Full Member Joined: Jul 29, 2009 Posts: 36

So some people add the second disc and caliper and don't make it functional? I always thought they needed that second disc-makes it look more balanced.

jetmechmarty

The 2nd disc and caliper does add quite a bit of unsprung weight. That's not a good thing, especially if it's to no advantage.

xsleo

When using two of the later style single piston calipers you will need a 14-16 mm m/c. Any smaller and you may run out of lever travel before the brakes work.
The m/c from the pre 76 with the two piston caliper will work well with two of the later single piston calipers. I used on just fine.
I'm using the m/c from an 82 Seca, it came from the same bike I got the clutch lever from.
I'm using the clutch lever because it pulls easier and pulls slightly more cable than the stock 650 lever.
I had to have the levers match.

grinder · Full Member Joined: Jul 29, 2009 Posts: 36

I picked up a pair of slotted rotors today from xs1100's.One is from an 80 and one from an 81. The rotors are stamped L and R. If you bolt the rotors up the slots do not align looking through one rotor to the other. From some photos i've seen this looks correct. Can anybody confirm this? It's not a big deal, I just think it would look better if the slots on the rotors aligned. Not sure if they changed something or thats the way it is.
Thanks

pumps

I'm curious if you hold them back to back the slots line up? Doesn't sound like they would.

jetmechmarty

I don't have access to my bike right now, but I do have an XS1100. As I recall, the slots do not line up as to look through from one side to another. The slots start from near the hub and go aft and out board on the rotor. This photo might help.

pumps

CalAl be sure to let us know how this goes as eventually I'd like to add a disc to the from of my 77 too.
jetmechmarty- nice looking 1100. There have been several for sale here recently on CL from a guy who has a small collection of them and a few others. I wouldn't mind having one if I had room.

grinder · Full Member Joined: Jul 29, 2009 Posts: 36

Back to back they don't line up. I wasn't sure if that's the way they are or you have to get a matched set from the same year bike.

jetmechmarty

Look at the photo of my bike. The rotors line up just like yours.

xsjohn

Think I heard marty mention some time ago that 2 of those heavy rotors will be a lot of unsprung weight.....(slotted stop way better anyway).... for me one slotted with the right MC and a good break line might be a better choice on an XS650. . . the second one being a good spare for the future....even one can be bumpy at times with the cast wheel I have found........

god I love my 8-1..........

xsjohn

grinder · Full Member Joined: Jul 29, 2009 Posts: 36

Yamaha put duals on the xs's back then and these rotors should be a little lighter. I take my bike out for a ride in the countryside on a nice sunny day(if I can find the time). I don't think a little more unsprung weight is going to matter for my riding style. I think the bike looks more balanced with the dual discs. I've always wanted to do this since I bought the bike new in 77.

xsleo

When I put 1100 rotors on my 75 they measured 5 mm thick, the 650 rotors were 7 mm thick.
Being thinner and slotted the weight is much less, enough to offset the extra caliper? I haven't weighed the parts to be sure.
I like the set up on my bike, they work great.

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