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Discussion Starter #1
So I recently replaced the master cylinder on my 2009 because I slowly lost lever pressure on the original so I figured it had gone bad from sitting (bought the bike with 5500 miles. Had been neglected) I thought it would be a simple bolt on, fill up, bleed and be done, but for some reason I get no fluid pressure out of the port when I pull the lever. It also seems the little button that activates the springs in the cylinder is not coming all the way back out on its own after pulling lever. Even straight out of the port on the back of the master, I get nothing by pulling the lever.

I read somebody suggesting a vacuum at the bleeder nipple method. Just suck until you pull solid fluid or..?
 

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Discussion Starter #4
Did you bleed the master cylinder by itself, not connected to the brake line?
I tried, but with the banjo off, I get almost no push or pull from the port coming directly out the back of the master cylinder.
 

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You can use that brake bleeder to pressurize or to pull the brake fluid through the master cylinder. I have had it since high school and have used it on all kinds of vehicles.
 

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Discussion Starter #7
I
You can use that brake bleeder to pressurize or to pull the brake fluid through the master cylinder. I have had it since high school and have used it on all kinds of vehicles.
I actually have one of those. I tried using it on the bleeder valve orifice but had no luck pulling anything through. Do you typically do this on the bench?
 

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I actually have one of those. I tried using it on the bleeder valve orifice but had no luck pulling anything through. Do you typically do this on the bench?
If you can't pull anything through you can also put brake fluid in it and pressurize it. In fact that is part of bleeding a master cylinder is force the fluid in the opposite direction of the actual flow. After you have blown all of the air bubbles out then pull the brake fluid back through. I usually just do it on the bike.
 

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Can a new TW master cylinder's piston and seal be confirmed to be wet, clean and clear of any manufacturing debris before attempting use?
Back in the days of dinosaurs my high school auto shop taught to never trust cleanliness of new hydraulic parts but to disassemble & clean with fresh fluid whenever possible plus make sure one-way or check valves were wet and not sticking.
 

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Discussion Starter #10
I reverse bled this on a bench with the syringe tool, put it back on hooked all the lines back up and was getting sporadic fluid pressure at the bleeder nipple, but nothing seems to transfer into pressure at the caliper pistons. Im stumped and about to push this thing off a cliff.

I just finished going through the entire brake system on a cadillac that had been sitting for 30 years and it gave me less trouble that this POS!
 

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I have rebuilt so many vehicle master cylinders I lost count a few decades ago. But, I've never had an M/C master cylinder apart. Are they that much different? I mean, there's reservoir, a piston (many times there's two in vehicle master cylinder) and, the outlet port(s) and in some master cylinders, there's a bleed port or ports. Maybe one of these days I'll have mine apart and learn about it. As for the syringe, wow, $15, I think I've seen ones just like that for about $3 at various supply outlets.
Scott
 

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Bad part. I got a bad brand new master cylinder for my car. After 2 days I gave up. Took it back a got a remanufactured one. Worked perfect. Push yours off a cliff. Get another one. Save some grief.
 

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I reverse bled this on a bench with the syringe tool, put it back on hooked all the lines back up and was getting sporadic fluid pressure at the bleeder nipple, but nothing seems to transfer into pressure at the caliper pistons. Im stumped and about to push this thing off a cliff.

I just finished going through the entire brake system on a cadillac that had been sitting for 30 years and it gave me less trouble that this POS!
Are you getting enough pressure to finish getting the master cylinder bled? On the Hondas hydraulic clutch they say there is a small port and if it isn't working correctly to clean it with a small pin. You may take a look in the bottom of the master cylinder and poke a small pin carefully through the ports to see if there is anything clogging it. Do that another day though. Frustration isn't worth messing with.
 

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The 'trick' that comes to mind first is the tiny bleed port in the master cylinder. The master cylinder cup closes off the tiny hole when you pull the lever. If the cup doesn't come back far enough (spring problem), or the hole is plugged (or not drilled through), or the master cylinder is assembled wrong (cup backward), then you get no juice into the chamber.
When you just barely touch the lever, you should get a little bubble of fluid (or air bubbles) inside the fluid reservoir. If you get nadda, then there's probably something out of whack. If you don't have much fluid in the reservoir (about 1/8-1/4" over the bleed hole), when you pull the lever, a little fluid should fountain up (might squirt you in the eye..be careful).
Pictures..https://www.pinterest.com/pin/686658274422268185/
 
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