'72 Master Cylinder rebuild....YOUNG, MIDDLE & OLD TIMERS PLEASE HELP!

[tadd442]

I picked up a NOS rebuild kit for my master cylinder (1972) Yamaha part # 1A0-W0041-00. When looking the pieces over, they do not match the parts in any of the diagrams/exploded views that I've seen.

Have the kits been revised?

I have:
A plunger/piston ( which for now, I will say fits as I need to clean up my bore)
A conical spring Which has a cap with a hole crimped onto the smaller end.
A snap ring Which I will presume fits.
A beveled seal Which I presume gets fitted onto the plunger/piston
A copper (maybe brass?) disk
A boot For the end that the brake lever set screw contacts
A beveled rubber plate with several notches on one side and a rubber dart on the other

 

[tadd442]

NOBODY? ANYBODY?

 

[tadd442]

bump?...

 

[Downeaster]

Perhaps a picture of your parts?

Everything but the copper "disk" (crush washer maybe?) and the "beveled rubber plate" sounds like normal kit components.

 

[jacksdad]

Has anyone got a diagram of how the master cylinder repair parts go together?

 

[pamcopete]

I have 5 motorcycles. As each one of them entered the garage, I ripped off the master cylinder and hoses and replaced with new. The caliper can be rebuilt as it is a very simple device and you can see inside every nook and cranny and use a kit to make like new. Not so with the master cylinder. Yours is 2012 - 1972 = 40 years old. Time to get a new one. When you squeeze the brake lever, you do not want any surprises.

 

[jacksdad]

I've had about 50 bikes and been riding for over 35 years....and never had a master cyinder fail! Of course, they do fail, and as you say these bikes are now getting pretty old (like me! )
Thats why repair kits are made. The problem with mine is that it had been sat for 20 years, many of those without fluid inside, so the seals had all gone bad and when I pulled it apart the main shaft snapped causing the whole setup to fall apart! The bore of the cylinder is completely unmarked, perfect, so a kit will make it good as new....if I just knew the order it goes back together!
I think Yamaha must have assembly diagrams as they supply repair kits, just need to find them

 

[gggGary]

Isn't this enough info?

Littlebill had a great series on overhauling master cylinders, but I can't find it now. I had no luck contacting little bill either.

 

[pamcopete]

jacksdad,

It's all about the risk and consequences. The risk of a master cylinder failing are low but the consequences are high. It's not something that you want to bet your life on. It's the same with the drive chain and tires on a motorcycle and yet people will shop around for the cheapest tires and chains and then spend $500 to paint their gas tank.

 

[tadd442]

For pics of what is supplied...
http://www.xs650.com/forum/showthread.php?t=20718

Gary, you will see that the parts do not look like the diagram.

 

[tadd442]

I have 5 motorcycles. As each one of them entered the garage, I ripped off the master cylinder and hoses and replaced with new. The caliper can be rebuilt as it is a very simple device and you can see inside every nook and cranny and use a kit to make like new. Not so with the master cylinder. Yours is 2012 - 1972 = 40 years old. Time to get a new one. When you squeeze the brake lever, you do not want any surprises.

Hense the rebuild!

 

[jacksdad]

tadd442 my repair kit is exactly the same as yours!
gggGary I've seem the diagram you've shown (thanks!) but its not detailed enough
pamcopete I hear you but where do you stop...buy a Hummer instead?

I've now got a Special master cylinder that works, its the sloping one so not suitable for me, I'm going to strip it and see how the parts should fit!

 

[gggGary]

After a search on here which included a deleted littlebill thread about a "rebuild" that did not go well... I found this link that inxs supplied. the link should get you through the rebuild I think, take and post pics! http://www.mikoede01.de/downloads/xs650.de/xs-wsh-de/5_Fahrgestell.pdf

It's a rather big pdf file but includes DETAILED pics and and how to on the early master cylinder (in three languages!)

 

[jacksdad]

I pulled apart my spare cylinder, here's the parts as they come out:

The tricky bit will be getting the piston seal over the end of the aluminium rod:

Also the 'top hat' that goes over the end of the spring is a bit difficult to get back in, I tried rebuilding the cylinder with the old parts, it needs to be pushed in sort of sideways and then eased round the right way up with a pair of tiny screwdrivers or similar, with plenty of fluid used as lube

 

[tadd442]

Nice, thanks guys! Any ideas about the copper/brass disk?

 

[jacksdad]

No idea what thats for!
Here's the new repair kit