New Master Cylinder and Lines, cannot get fluid to even bleed past master. Have Pics

estcstm3

estcstm3

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Hi All,

Im back (after finishing my electrical issues from another thread). I bought a new MC, SS lines, and Pads from 650 Central. I have a mityvac (vacuum bleeder) and I started to bleed my brakes. I couldnt get them to bleed at all (no fluid) so I took the banjo bold off on the MC itself with the mc half full and pumped the brake handle and no fluid came out? I then put my finger over the hole to try and build up pressure, again no fluid.

Whats the deal, did I get a bad MC, or is this normal for a new fully dry system?

Here are the pics of my MC. I also got new bars so I had to screw in the plunger bolt alittle so that it could clear my controls, could that be contributing to the problem?
 

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May have dry seals or something inside restricting flow from shipping. If you have the plunger in past the feed hole it wont flow

Posted via Mobile
 
Dumb question as I have never worked on a MC (or replaced one). How would I know if the plunger is going past the feed hole, is this something I need to adjust?
 
The 2 holes inside the res.the one closest to the banjo is the return the other the "feed" (odds are thats the wrong term) see if you can back out that adj screw for testing purposes

Posted via Mobile
 
Sometimes it takes a while to get fluid through the line and to the point where you can start to build any pressure.

I just replaced my brake line a couple of days ago and I had good luck filling the master cylinder and leaving the bleeder on the caliper closed.

If you pump slowly and flick or tap the brake line air will start to rise and will bubble out of the return hole in the MC. I just go back to it every few minutes and try again. Flicking tapping and pumping the lever (fast, slow, whatever - I just try to get air coming out of that return hole) Most of the air will come out of the system this way and you will get to the point where pumping the lever will start to create some pressure in the line.

Once you have a little pressure, fill the MC back up and bleed like you would car brakes. Pump it up, hold the lever, crack the bleeder and close it before you release the lever. Should go pretty fast once you get most of the air bubbled up through the line. It took me maybe 45 minutes to get a good solid feel to mine. I have a Mike'sXS MC that I think is the same model you have and I just put SS lines on.

Hope that this helps
 
I usually find myself working the lever an awful lot with my finger blocking the banjo hole at the master. Sometimes it takes quite awhile, but then it comes up real quick when it finally gets a little fluid moving. Then I put the line back on and bleed at the caliper. A couple times I was close to swearing, but it always works in time. Make sure the master is level when bleeding, they're not always level in use.
 
Don't start with the brake line full of air. Pre-fill the brake line on the bench. Pre-fill the caliper. Re-connect the full line and fill up the reservoir. Do some bleeding at the caliper, and within 5 minutes you have a hard lever.

Easy and simple. Use a syringe to pre-fill the line and caliper.
 
estcstm3 said:
I also got new bars so I had to screw in the plunger bold alittle so that it could clear my controls, could that be contributing to the problem?
Click to expand...

Yes, I'd bet that's your problem

When the lever is at rest, the screw should NOT be touching the piston

If the screw is touching, its possible to move the MC piston far enough to block the compensation port in the MC

The compensation port allows fluid to enter the brake circuit when the lever is released

If the piston is blocking the port, no fluid will ever enter the brake circuit
 
I read on a tech article in Cyclesource that you could use a syringe to push brake fluid up the bleeder. Since air bubbles want to rise it is supposedly super simple. I've always used a vacuum pump to draw down as per usual in the past. Thoughts on this idea (not meaning to hijack)...
 
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First step is to remove that adjustment bolt and put the original back in.

Move MC assembly over on the bar until it clears the throttle assembly.

Make sure adjustment bolt is set so the lever moves slightly before engaging the brake piston assembly.

If this is a new MC as quoted, move the assembly and handle bars such that the top is as level as possible and you can fill it to at least 3/4 full.

Leave it for 5 minutes pumping occasionally to remove some air.

Now loosen the top banjo bolt slightly and start pumping until you see brake fluid oozing out. Re-tighten

Continue to the next fitting if there is one on the lower triple tree, if not do the one on the brake slave cylinder.

All the while pumping slowly and smoothly so you don't splash fluid on anything painted. If you do, a wet rag full of water will neutralize the brake fluid.

Always keep MC 3/4 full of fluid.

Then start using the slave cylinder bleed screw to get the remaining air out.

Hose and catch bucket required.

Always use new fresh fluid from a freshly opened container.

Patience is a big plus.

Good Luck.

Oh, and when you get this done, then go back and fix your adjusting screw and MC to Throttle Assembly positioning.

Second OH, reason it's not working now, that piston in the MC has to have clearance from the lever so it is able to travel all the way out otherwise it blocks that tiny hole that feeds it. Adjusted the way you did has the piston either blocking the hole or past the hole so that either way no fluid is entering the piston chamber.
 
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Things I've noticed over the years.

As a rule most Master Cylinders (MC) never leak. Makes you wonder if they ever wear out if the fluid was changed every two years.

Can't remember ever seeing fluid dripping from the seals on the piston.

Biggest fault is fluid never being changed causing corrosion of the aluminum due to water contamination. It's the body of the MC that fails.

Common problem is the tiny hole that feeds the piston is plugged with crude from never changing the brake fluid. No fluid no brakes.

Second most common problem is rusted Slave Cylinder (SC) pistons. Not hard to tell why, water contaminated brake fluid. More leaks here due to high pressure and heat combined with the water contaminated brake fluid.

I wonder what the cure for all this is??????
 
Get a vacuum bleeder. Harbor Freight sells one cheap and it works great. Goes on the bleeder and creates a vacuum pulling the fuild through the system.

i found letting the system sit overnight with the bleeder open and a hose hooked to it into a jar will get the flow going too. The next day refill the master and pump it up.
 
Sorry TwoJugs,

But I think a vacuum bleeder system is not required and just an added expense for such a simple braking system.

Great for cars but a waste of money for most bikers.

Recently did a BMW touring bike with ABS and integrated front/rear braking system, no vacuum bleeder required.

Steep learning curve to learn how to bleed ABS systems.

But once I had the correct manual and understand what was going on things went well.
 
I agree with Brian902.....................there's no need for vacuum bleeders on a motorcycle. You're not bleeding air from 20 feet of brake line such as on a car or truck.

A bike's line is very short. Pre-fill the line on the bench, and then its about 5 minutes to a hard lever.
 
Hi All,

I am getting great replys but I am not sure everybody read my entire post.

My problem is without the brakeline even connected, just the master cycliner with the banjo bolt removed, I cannot get fluid to drain out. I even left overnight with a glass to see if anything would weep through and nothing. Again this is just at the MC (forgot the line for now). I have pumped the brake lever 50 plus times, slow and fast, and left the MC overnight without the banjo bolt and no fluid.....

Second point is I already own a mityvac (vacuum bleeder) which is super simple, and takes all of 5 mins to bleed the brakes. However that is assuming you can get fluid out of the MC which is where I am stuck. I will move the MC away from the controls and mess with the plunger screw I'm guessing backing it out to make sure fluid can get past.


I am going to follow up on this suggestion:

Originally Posted by estcstm3
"I also got new bars so I had to screw in the plunger bold alittle so that it could clear my controls, could that be contributing to the problem?"

Per FB71
"Yes, I'd bet that's your problem.
When the lever is at rest, the screw should NOT be touching the piston.
If the screw is touching, its possible to move the MC piston far enough to block the compensation port in the MC
The compensation port allows fluid to enter the brake circuit when the lever is released
If the piston is blocking the port, no fluid will ever enter the brake circuit"
 
Last edited:
estcstm3 said:
Hi All,

I am getting great replys but I am not sure everybody read my entire post.

My problem is without the brakeline even connected, just the master cycliner with the banjo bolt removed, I cannot get fluid to drain out. I even left overnight with a glass to see if anything would weep through and nothing. Again this is just at the MC (forgot the line for now). I have pumped the brake lever 50 plus times, slow and fast, and left the MC overnight without the banjo bolt and no fluid.....

Second point is I already own a mityvac (vacuum bleeder) which is super simple, and takes all of 5 mins to bleed the brakes. However that is assuming you can get fluid out of the MC which is where I am stuck. I will move the MC away from the controls and mess with the plunger screw I'm guessing backing it out to make sure fluid can get past.


I am going to follow up on this suggestion:

Originally Posted by estcstm3
"I also got new bars so I had to screw in the plunger bold alittle so that it could clear my controls, could that be contributing to the problem?"

Per FB71
"Yes, I'd bet that's your problem.
When the lever is at rest, the screw should NOT be touching the piston.
If the screw is touching, its possible to move the MC piston far enough to block the compensation port in the MC
The compensation port allows fluid to enter the brake circuit when the lever is released
If the piston is blocking the port, no fluid will ever enter the brake circuit"
Click to expand...

Follow FB71's advice, and that should solve your problem. Yes, I understood that the fluid was not leaving the M/C................I added the info about easy bleeding as an additional aid to help after you follow FB71's instructions.

If I remember correctly, someone had previously posted that they actually found one of the small holes, in the bottom of the reservoir, blocked from the factory. So, if repositioning (increasing the stroke) of the M/C piston does not work, do a very careful inspection of the 2 small holes. May need to remove the piston from the cylinder in order to check that the holes are clear.
 
Thanks again. I was not referring to anybody specifically, I just noticed I was getting alot of advice (helpful) that was still several steps of ahead of where I was. Hopefully once I get the plunger situated the rest of the bleed will be non eventful.
 

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