master cylinder

[jay man]

I cant seem to get my master cylinder to work,  I took off the brake line and depress the lever and nothing comes out, even though its full..?  Any ideas.

[RobTx]

The hole in the bottom of the reservoir is likely clogged up.  It's relatively easy to rebuild the master cylinder, just need a pair of snap ring pliers.  Check the bore for any rust, clean out the hole in the bottom of the reservoir and put it all back together using brake fluid as a lube.  Be careful not to tear the rubber parts putting the piston back in.  If the bore is rusty, it can be cleaned up with some fine emery cloth or wet sandpaper using brake fluid as a wetting agent.  Rinse with brake fluid and put it back together.  Or you can just take the top off the reservoir and clean out the hole in the bottom with a toothpick or something, but you could get debris in the master cylinder, and maybe scoring the wall or tearing the rubber seal.
Rob

[mrsoup]

Or, you can upgrade your system for a little change if you want to improve braking performance. The Honda CBR600F3 master cylinder is a direct bolt on. The angle of the resevoir is even better than the stock unit on my 83. The only modification I had to make was to adapt the brake light switch wires to the Honda spade connectors, the brake hose bolts right up. It really improved braking 'feel' and made the Vision a comfortable 'two finger' brake application. Available in the $20 dollar range at salvage yards.   :)

[Waapman]

How do take it apart?  Do I need to take off the whole handle bar??  I took the reservoir lid off but Im lost after that.
 thanks......

[RobTx]

Waapman, take off the brake lever.  (It's easier to do all of this if the M/C is removed from the bar).  You'll see the piston and the snap ring if you look into where the brake lever presses in.  There is a spring behind the piston that will push everything out.  Follow the rest of the instructions above, assembly is the reverse.  Email or post again if you have questions.
Rob

[Waapman]

Got it all apart, the snap ring snapped in two pieces as I was removing it, it was old and rust....  The rubber gaskets were pretty torn up as well.  I guess I;ll try to find replacement parts.  At the same time Im gonna try to locate a Honda CBR master cylinder.
 thanks for all the help... before long I'll actually get to ride the thing!

[Waapman]

Anybody know of a good place to pick up a cheap rebuild kit?  or a good used one??

[Lucky]

Check your local non-dealer, or smaller motorcycle shop, they usually carry after-market stuff like K&L.

There is no such thing as a good, used, rebuild kit unless it's already in your M/C...  The LAST thing you want to skimp on brake parts, since your life depends on it right? :)
--Lucky

[RobTx]

They list 2 different kits here: https://www.partsnmoreonline.com/PNMSite/Master%20Cylinder%20Yamaha%20125-600.htm
I'd call and see which on fits yours.  One is $18, the other $16.
Rob

[Rick G]

I have several master cylinders in servicable condition . email me  at rgcdn@juno.com