78 Rear Master cylinder rebuild kit

[radio one]

I have a 78 XS400 rear master cylinder that needs a rebuild kit. I read online that the sr500 and xs400 master cylinders are interchangeable. I bought the sr500 kit, but it is too small. Does anyone know where I can get a rebuild kit specifically for the xs400. Thanks for any help.

 

[bcware]

I looked for about 30 minutes for you; no luck.

It looks like the part number for the kit is 1U4-W0042-50

Many, many posts exist on this subject with no solutions posted. At best a few people said they snagged the last one in stock from wherever.

I'd consider converting to a new aftermarket or rear master cylinder from another bike.

If it must be original be prepared for a large markup if anyone has one in stock. A few people mentioned prices over $100.

Sorry I couldn't help more.

 

[Lego]

Hi.. I am dealing with the same issue. My rear master is no working. As bcware says, no rebuild kirs are available to buy. I will try just clean the old one and reuse it and hopefully that will help. If not, replace with rear master from another bike with similar cylinder diameter.

 

[drewpy]

http://www.cmsnl.com/xs400f-1979_model8710/cylinder-kitmaster_1u4w004250/#.VKbSRXtp6Po

http://www.preferredpowersports.com...Motorcycles&make=Yamaha&year=1977&fveh=176846


if you just want the cup;

94 Dodge shadow wheel cylinder kit. (5/8") has the cus in the kit

 

[radio one]

Thanks for the replies. After spending several hours on the internet, I reached the same conclusion. I guess I will see what I can do with the parts I have and if no success will start looking for a new MS.

 

[84tele]

I had the same issue but ended up getting my rear MS to work using the original parts. All the rubber was in good shape while the metal was quite corroded. After cleaning up all the metal as best I could it still didn't want to work. The plunger was sticking and not springing back like it should. So, I took a wooden dowel and wrapped some 0000 steal wool around the tip and taped it on with masking tape. I secured the dowel in my drill and wet the steal wool and reamed out the bore really good. After that, it's been working perfectly.

I'm convinced the rear MS parts just no longer exist. So, it's get the old one working or mod in a replacement. Luckily, I got mine working. Good luck!

 

[Sesty]

the return hole in my rear was clogged with rust and old fluid crude. took it a apart, cleaned up the metal bits and used a bristle of a wire brush to clear out the return port... good as new now..