1981 XS1100LH Midnight Special Rear Master Cylinder rebuild.

[BillAnderson611]

I am looking for anyone who has any part numbers for, or access to a rear master cylinder rebuild kit for the 1981 XS1100LH Midnight Special. This kit has apparently been discontinued for a long time and is extreamly rare. I have calls into multiple shops to keep an eye out for one but nothing yet. I am assuming I will need to find new old stock. K&L doesn't even have a part number for it that I can find.

If anyone can help me with this I would greatly appreciate it. What I know so far is that between 80 and 81 Yamaha changed the rear master cylinder on the midnight specials. Irritating because I can find kits to rebuild rear master cylinders for the 80 midnight specials. Any other tidbits of info would be appreciated as well.

Thank you,
Bill A.

[DGXSER]

The LH or 81 MNS uses the same rear MC as the XJ1100. They both have the linked braking system. I believe you may find one by contacting Chacal over at the XJbikes.com site.

[bikerphil]

Pretty sure the XJ11 and 81LH rear masters have a different bore size so the kits are not interchangable. There is a member here who had the same issue of not being able to find a rebuild kit, so he swapped in an XJ11 rear master which is also set up for the linked brakes.

A lot of times, a rebuild kit is not necessary, just a good cleaning will suffice, YMMV

[mack]

Parts

Are you just in need of the plunger assembly, or do you need the proportioning valve as well. Rasputin just did his and will have source and numbers handy.

[BillAnderson611]

I was going to just do the plunger assembly and deal with valve if I had to later.

[Rasputin]

Unfortunately my supplier was into NOS and he no longer exists in my mind... Craft setting in. I remember it was either on ebay or a NOS supplier from the site that someone recommended.
As for the part number... I threw the box out when I installed it so you will have to get the part number elsewhere. Many parts fiches have it shown. Wish I could help more!

[Prothec]

I replaced the plunger on the rear MC on my XJ. I completely tore it down for a good cleaning as well. Just make good mental notes while disassembling the proportioning valve. The manual states it is not a serviceable part, so doesn't exactly give much direction.

It took quite a bit of head scratching when trying to reassemble before finding a single photo in the manual that kind of helped. I assume I put it together correctly because it still works!