Kawi2strokes.com Forum

I am in the process of beginning the brake refurb on my RZ . The master cylinder was pretty nasty and the brakes are dragging. The calipers will come off soon to be cleaned well to include bead blasting the bodies and painting. Upon removal I noted two small holes side by side inside the master cylinder as depicted. The one on the right under the #2 is open and you can see the mechanism moving when you squeeze the brake lever. The other appears to not go anywhere? Or is it corroded closed or blocked?



Thanks in advance to any and all who reply.

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I Love the Smell of Blue Marble in the Morning!!!
Tim Steele in Front Royal, VA
Home of the Phoenix Project
Stay in it when it comes on the pipe, no need to be scared...

The other one has a tiny hole that goes through, and it's very important for that hole to be clear.

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If it surges, that's normal, upshift.

Off the top of my head, I think the other hole is a breather, it's a VERY small pin-hole.......... At least that is the case on Kawasaki (round) M/cylinders..... anyone else? edit....Wot Jim said!

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"One day, your life will flash before your eyes. Make sure it's worth watching." : anon.

That's the hole that ensures that there is no pressure left when you fully release the lever. It's also the one that didn't get uncovered when Jason installed a non-stock lever at Deals Gap this year. The next day, things warmed up, the brake dragged, things warmed up more, and it wasn't long until his front wheel locked, causing him to crash.

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If it surges, that's normal, upshift.

New master cylinder it is then unless I can get it open. Thanks to all.

_________________
I Love the Smell of Blue Marble in the Morning!!!
Tim Steele in Front Royal, VA
Home of the Phoenix Project
Stay in it when it comes on the pipe, no need to be scared...

I'd think you could get it open if you clean the indentation and then locate the hole and stick a small wire through it. Worst case you can use something like a #80 drill bit by hand.

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If it surges, that's normal, upshift.

I will give it a shot

_________________
I Love the Smell of Blue Marble in the Morning!!!
Tim Steele in Front Royal, VA
Home of the Phoenix Project
Stay in it when it comes on the pipe, no need to be scared...

I took my trusty Singer needle equipped GI sewing kit to the shop and the little hole is now open. So I think the stock master cylinder is saveable... I am also exploring other options after reading about some who have changed from the stock 16 mm to a 14 mm master for better feel..... Interesting.

_________________
I Love the Smell of Blue Marble in the Morning!!!
Tim Steele in Front Royal, VA
Home of the Phoenix Project
Stay in it when it comes on the pipe, no need to be scared...

I use a single strand of small gauge electrical primary wire stranding to open those tiny holes. Nice thing is, you can use the single strand still in the insulation after stripping the insulation off the end of the wire, then selecting the one strand to use, and after use, put the strands back together and still use the wire for electrical stuff.

When I bleed a brake system, I do the normal pressure to the wheel cylinder to basic fill the entire system, then let the system sit for a time, allowing any air left in the system to rise within it. Then, I finish bleed through that tiny port all the remaining air. I hand hold the master with the lever end higher than the outlet, then gently pump the lever. Air will come out that hole if there is any left in the system. My 1986 Safari van has a factory 5 speed in it, and hydraulic actuated clutch. The master has cold weather issues, and I bleed it the same way, remove from firewall, tilt pedal end higher than output end, gently push piston, air evacuates through the pressure release port, back to 'works as new' again.

Jim is right on target, pressure release port. Wrong lever config, does exactly as he outlined, slip, slide, WHOA, whammo, crash, bang......ouch.