One port open, one port uhhhhh, what...?

[madjap]

72 650, stock master cylinder. Issue: Very firm pressure at master cylinder, not much pressure at caliper (seemingly). Basically, I've got a very FIRM brake lever with not much lever movement, but not much 'stopping power'. New Goodrich braded steel front brake line, rebuilt caliper. When I pulled the master cylinder cap off initially, I could see the larger of the two ports easily and could see the piston working back and forth in it as I worked the brake lever. The smaller 'port' was harder to define. I scraped around and it appeared (it's like 3/8's of an inch in front of the larger port) BUT I can NOT seem to get anything thru the smaller of the two ports to clean it. No bubbles thru it or movement like fluid is pumping thru it. So, I pulled the master cylinder apart (surprisingly easy and not gunky inside BUT signs of pitting on the steel parts shows it has been rusty in the past and maybe a P.O. had cleaned it up? Anyway, I cant seem to get anything THRU that smaller port to clean it. 100 PSI wouldn't do it, my smallest torch tip file just STOPS it itas if it's bottoming out and so I'm wondering, WHAT THE HECK? Does that 'port' run to the side(s) or something and my tip file obviously won't bend to follow the part of the port OR WHAT? Anybody know? Got it soaking in some penetrating oil now overnight. COULD NOT get air to blow thru it and I put a dummy plug in one end, a 5/8 OD rubber hose in the other and got a GOD seal and NADA! The larger port blew right thru, but when I plugged IT off with my thumb I got nothing thru that little port. Any advice or answers on this issue? Thanks! MADjap

 

[650Skull]

Have a look through this. Info on the 72 as well

http://www.xs650.com/forum/showthread.php?t=7862

 

[gggGary]

That second port is ( and must remain) TINY, smaller than your smallest torch cleaner pin or the smallest number drill. The hole is made at the factory by using a special V shaped cutting tool that just pierces the piston bore. Several aftermarket MC's have been found with the hole not complete! Endless fun ensues.

One way to clean a stubbornly clogged hole, sharpen a piece of stainless steel safety wire on the grinding wheel. I probably could go get a small sewing needle........

even better is a 90 scribe or scriber.



A very handy tool!
Working up into the hole from the bore side. As you can imagine whatever is blocking the port settled there from the reservoir side, and needs to get pushed back that way CAUTION! do not scratch the piston bore or enlarge the hole!

 

[madjap]

Have a look through this. Info on the 72 as well

http://www.xs650.com/forum/showthread.php?t=7862

Yeah Skull, I read thru all that prior to posting but it didn't answer my question, BUT gggGary just did, thanks!

 

[madjap]

GREAT! Thanks gggGary! Gonna try the sewing needle tonite and then maybe try some random sex with a comely busty brunette, see if THAT helps....