Still can't bleed front brakes after adding NEW Master

I'm stumped.

I replaced the double lines with one single steel braded line. Rebuilt the caliper, and installed a brand new Master Cylinder assembly from MikesXS.com

I still can't get the brakes to pressurize. I put three resevoirs through, no more are coming out of the bleeder line, but there's still no pressure.

The only thing I can think of is that the new line has a wider inner diameter then the old one. I checked around, talked to some hydraulic specialists that I know, and they said the size of the pipe should matter. It just means your just carrying more fluid in the line then a smaller one.

What else can I look at?

 

If you meant to write:

"they said the size of the pipe shouldn't matter."

You have been told right!
Internal diameter of hose doesn't matter.

Try to shake hoses or tap on them lightly with spanner or something. If you see bubbles coming out in oil tank there is still air in line.

That will help to release trapped air.

 

Yup, that's what I mean to say.

Oh man, I've tried everything. My hands are killing me from pumping that brake line.

 

Wrap a bungee cord around the brake lever and let it sit overnight with the lever compressed and the resevoir. Then try in the morning. This allows the air to float up to the resevoir and escape. If this doesn't work then find someone with a Mity-Vac. Harbour Freight has a similar brand for about $20.

 

make sure your brake cable is properly adjusted and you are getting full travel of the piston

 

Totally forgot we had a brake bleeder pump in the shop.

Hooked it up, put and rubber band around the handle holding it down, hooked up the pump the bleeder value, opened it... and I've got to pump like mad just to get a little bit of oil out. Something's not right.

 

Still stumped.

Using the brake pump, I got all the air out, it's perfect. Still no pressure. Could there be something wrong with the caliper? To test this, I took the line off and put compressed air to the caliper. It closed quickly and held the pressure.

I have no idea now... It's driving me insane. Help, anybody.

 

With the caliper off, & disconnected, does the brake line push oil when you squeeze the lever? Is it a strong pressure? See if you can adapt a pressure gauge to it for a measurement. You've got to have pressure on that line.

Now, the caliper - off the bike, cyl back in all the way. Fill the caliper reservoir completely. Put your air tool on it - Does it slam out? Easily?

Again, caliper off the bike, fill the reservoir with the cylinder OUT. Closed bleeder, tap on it with a plastic mallet to dislodge all the bubbles inside.
Fill it until your sure only fluid is inside.

Now make sure the lever reservoir is full, plug up the hose end, put the cap back on the full reservoir.
Now pull the hose plug, connect the hose & caliper leaving it a bit loose while you allow fluid to escape the fitting as you push the caliper cyl. slowly back in about half way or less as you tighten the fitting.
Open the lever reservoir lid and slowly push the caliper cyl back in, while watching the oil rise in the cup. Siphon off what you need to keep from spilling over.
Close the lid on the lever reservoir cup & test the system - Should have easy movement of the caliper cyl.
Now clean & mount that caliper with some pads, and you should have solid brakes.

 

Dan,

Thanks for the ideas. I'll try those out tomorrow. It's a new line, but ya never know. it could have a small air leak, although the entire line is bone dry with no signs of fluid. With your info, my guess is there is a big air pocket in the caliper. I'll take it off tomorrow and fill it complete.

Thanks,

 

I assume the first post above meant you pumped 3 master cyl reservoirs of brake fluid down the line or it had to got someplace??? But your last post said the line is bone dry which is confusing, where did the fluid go, maybe it needed more.

When I replaced my dual brake system with SS lines I did have one heck of a time getting the thing to pressurize.

First I mounted the calipers and filled them and the connecting section of brake line via the bleed screw and a syringe.
I connected those lines up with a full reservoir and figured it would go real fast!
It didn't, I found out the master cyl wasn’t pumping, I had to pull a vacuum on the output line and pump before it started to pump fluid. Then it took a whole bottle of brake fluid and a long amount of pumping before I got the system to work.
On my bike, by accident I located a small leak on one of the brake line connections, got that fixed and bingo brakes worked.

I would check each joint in your system with a clean tissue, wipe the joint if the tissue gets wet, you got a leak and the system won't pressurize.

 

Someone forget to put seals in that new master cylinder by any chance?

 

Nick,

Sorry, by bone dry, I meant the outside. No leaks found.

I'm going to get a syringe and a new bottle of brake fluid tomorrow and start again. The master cylinder has lots of pressure, that's what's making it so strange.

 

I can't imagine how a Brake Fluid Leak could possible go unnoticed on a Motorcycle.

Get a Syringe.
Bulb type. The kind for Ears.
Remove the Bleed Screw.
Crack the Banjo Bolt on the Caliper and use the Syringe to Fill-up the Caliper.
Tighten the Banjo.
Leave the Bleed Screw out and put you Thumb over it.
Have an assistant work the Brake Lever.
They Pull the Lever ... You remove your Thumb.
You Cover the Bleed Hole Tight ... They release the Lever.

This should have Fluid moving out of the Master Cylinder in just a few repetitions.

If fluid isn't coming-out after 8 repetitions and there's no pumping "Feeling" happening at the Master.

The Master's is vacuum-locked or Bad.

 

Make sure the small secondary hole in the master cylinder is not plugged.

I also had a hard time bleeding my new braided lines. I found that filling the master cylinder up completely, then putting the cap on before pumping it up solved the problem. immediately.

 

I had a similar problem a few years back with all original brake parts. I couldn't get it to pressurize until I put the cap on either. Pita having to take the cap on and off to top up the resevoir, but it got the system working.

 

Now, I'm even more stumped. I pulled the caliper off and pushed oil through the bleeder up into the master cylinder. A lot of air came out. Great!

So now, if you pull the brake handle, the piston does move. Maybe 2 or 3 mm. Not enough to close down on the disc. I wonder if maybe MikeXS sent me the wrong one. Doesn't seem like there is enough movement of fluid to push the piston out enough to grab the disc.

 

Nope, Mike sent me the right one. 13mm bore, same as stock. Ahhhh, can't figure this one out.

 

I recently went with the braided s/s line and had a similar problem in not getting my system to pressurize.
The problem was a lack of travel on the brake lever adjustor screw. Once I removed the lever and operated the brake plunger manually, the system pressurized immediately.
And the difference in brake lever feel is incredible. With the 2, old rubber lines, the brake lever adjustor was about 95% IN (no more adjustment possible), and the feel was somewhat spongy or soft. With the braided line, the adjustor is about 95% OUT, and the feel is FIRM!

 

Hmm, mine is adjusted all the way in!

 

Let's hope you've found your problem!!
More lever travel was my first thought before I read the next post by Dispatcher.

I'm going to put braided hose & a fresh Master on my bike soon, so it's great to see this discussion.
Dan

 

OK, WE HAVE PRESSURE. What a Nightmare.

I took the caliper off, leaving the pads still attached. I then found something to take the place of the disc, but the catch was to find something about 4 or 5 mm smaller. In this case, it was a screw driver.

I then stuck that in the middle of the pads and put air to the caliper. It clamped immidiately on the screwdrive. Once I stopped the air, it realeased ever so slightly.

I then filled the caliper with using a syringe making sure there were no air pockets.

Next, I attached the line to the caliper, and then put the caliper on the bike. The pads were now rubbing the disc. They weren't before.

Again, using the syringe and a modifaction to some tubing, I pumped oil through the bleeder up the line and into the master cylinder. I put three syringe fulls through until there were no bubbles.

Topped up the master cylinder, made sure the travel screw on the brake leaver was all the way in, and BAM! We've got pressure.

I ended up having to take the leaver adjuster screw out, remove the locking nut, and put it back in so it could travel the full distance. I'll have to replace the screw with a longer one so that I can put the lock nut back on for safety.

Now the question is how much pressure? It still seems soft, but I understand the brakes on Maxim's were soft right out of the factory.

 

Just to be confident that you're A-OK.

Look on the Rubber Expansion Reservoir.
Is there a Notch that should be lined-up with a Vacuum break on that cover?

I guess from looking-over these Brake Threads ... you have that Pincher-style Caliper. That's not considered to be the finest Caliper ever designed to do braking. But, with those new brake lines you installed; you should be able to get more gripping out of them ... than the old lines could provide.

How well is it working? Are you going to do some additional bleeding; just to be sure the lines are totally evacuated of air ... or, do you think you nailed it?

 

Rick,

Having trouble picturing what you're describing regarding the rubber expansion Reservoir???

Yes, it's the old pincher style. It seems to be working well, but I've only had it in second gear. I had an openning to get my new tires put on so I had to take the tires off ASAP.

I'll report back soon.

 

The Expansion "Diaphragm" is the Rubber Gasket under the Master Cylinder Cover. It expands to keep the fluid from sloshing-around as the pads wear and the level decreases.

Some Covers are "Vented" with a very small notch ... that often fills-up with grime and disables the Diaphragm from unfolding as it should.

Its a very small notch on the cover. Sometimes overlooked because its soo small.

 

Thanks Rick, I'll double check that.

 

Something still isn't right. I think the brakes are too soft. I had my brother check them out, and he agrees they are way to soft. I can pull the handle right down to the bar pretty easily. Although there's stopping power, I feel that it's not enough under higher speeds.

 

Usually because there is air in the system. Air will compress, hydraulic fluid will not.


Dan

 

Hey Dan,

I bled the lines over and over. I went through probably 1/2 quart of no bubble line bleeding. I figured that would have been enough.

Well, I'll bleed them again.... and again just to make sure.

 

Tap on everything to dislodge trapped air bubbles. They stick to the walls of the hoses & chambers.

Dan

 

Take a small line from the ones you must have after the switch to stainless.

Seal-off one end with a bolt and a couple good-sized plumbing rubber washers.

Hook-up the other end to the Master.
Loosen the bolt on the washers and bleed that small section of hose as a test for the Master putting-out as it should.

After all this fussing-around ... that Master Cylinder is giving me a headache and I don't have one like it to help figure what' not right.

If you keep bleeding ...
And,
Nothing's LEAKING
The Master Cylinder is where you focus the spotlight!

 

lots of info here an I just need to add I have had to take the master off an rotate it at the same time of pumping the lever to get all the bubbles out seams they like to find pockets that can't be pushed out.
,,,,I also do the same for the calipers,,,
I think it's been said before I also do what I guess could be described as a reverse bleed I get the caliper pistons out then push it back in forcing fluid back up at the same time rotating the caliper an lines to get the bubbles to rise instead of going down witch is just what they don't want to do,,,,,
I have seen systems that will not bleed bolted up get your brain thinking like bubbles trapped in there,,
just my 2 cents but if it don't bleed right away I go through it this way,,,Dan

 

Look ...

Don't even bother with hooking-up a section of Brake Hose.

Get a bolt with the same Thread Pitch as the Outlet of the Master Cylinder and Plug-off the Outlet.

Have the Master Cylinder at least half-full and work the Brake Lever with the Bolt preventing fluid from leaving the Master.

If if feels like the Lever wants to develop some resistance ... Pull the Lever and let fluid bleed-out the bolt threads by loosening it a bit.

The ACID TEST will be the Brake Lever becoming Firm or Not.
If you get some HEAVY Resistance and even a point where you cannot Pull the Lever ... the Master is Good.

No favorable results ... Lever still Spongy or a Sloppy Pull right back to the Grip ...

That Master Cylinder is NO GOOD!

Simple as that!
Bottom line.
Bedrock.
Ka-put
Done
Bad
NG

 

Rick,

easy test. Thanks. I'll try it.

Dan

 

FYI:

My stock XJ650J is quite firm. There's a good gap between the grip and the lever when it's pulled as tight as I can squeeze.

I'm with Rick, I wonder if you have a problem with that MC. Find a way to plug the outlet (a piece of the old brake line will be great as Rick suggested). The lever should move very little.

Another thought, is your lever bent?

 

I had my front wheel and caliper off yesterday to free up the rotation of the caliper and do a few other things. I ended up using a c clamp to compress the piston before putting it back together.

This morning I noticed I had that spongy feel again, and could squeeze the lever quite close to the handle grip. I knew there should be no air in the system, but in case that was the problem I tried something new to free up any bubbles and let them rise.

With the bike on the centerstand I sat on it and rocked my weight back and forth to bounce the front end up and down a bit, being carefull not to roll off the stand of course. I could hear the gas sloshing around in the tank, and I would stop and work the brake lever a few times, then repeat.

Very quickly my brake lever returned to it's normal feel of bottoming out fairly solid (still has rubber lines) well before it reached the grip. Braking is dramatically improved now that I'm using both pads too.

I don't know if I disloged air or freed something up in the MC, but it might be worth a try for you as well.

 

Problem solved. Bled the lines for like the 100th time. This time, I moved the master cylinder to a position on the handle bar that made it perfectly level. Then, with the help of my brother... pumped the handle some more.. sure enough, a few bubbles popped out of the bleed screw. Front brakes are rock hard now.

Thanks for all your help everyone.

 

Amazing how much a couple of really tiny bubbles can mess it up, isn't it?

 

YAY!! You are now a qualified graduate of the school of Hard Knocks!
You should publish a "paper" on replacing brake components for the next XJCD version!

Well Done, your perseverance paid off.

Dna

 

Welcome to Motorcycle Wrenching.

I'm glad you finally got a big handful of brakes.

Just a few tiny bubbles ... that was it ... huh?
Imagine that?

Son..of..a..gun!?

 

Yeah, a few bubbles short of tossing the caliper and master cylinder clear across the shop floor. Took it out on saturday for a nice half hour ride with my wife. It was great. First time in my life that I didn't mind going the speed limit with a motorized vehicle! ;-) It was great just cruisin' around.

 

Teflon tape the bleeder screws!!! But be careful not to cover any holes!!

 

Making sure the MC is perfectly level seems to be the key to remember from this thread. I'll be sure to try that next time I encounter this problem.

 

Wow... just went through this today. Rebuild the front brake caliper and new brake pads. Had a heck of a time pressurizing the system. The trick is to fill the brake caliper as best you can with fluid first. Then make sure your brake adjust screw (at the master cylinder) is allowing full piston travel (mine wasn't). Then fill and close up the master cylinder to help get pressure for bleeding without squirting brake fluid all over the place.

Took about an hour but everything is working well now. I still want to replace the old brake lines as I'm sure it will improve braking capability even more.

 

I haven't read all the responses on this, but I have had problems with cycle brakes and clutch slaves not wanting to purge air like described...

First if your line goes "uphill" at all coming off the master cylinder, unclamp it and side it up the bar until the line runs downward...keeps air from trying to sit in the top of the bend and not move...

But if I still can't get pressure, I take the bleeder screw out, push a finger down hard on the hole, and begin rapidly pumping the lever (partially, you don't want to bottom out a master cylinder when bleeding)...keep pumping and lift your finger periodically and you'll get a puff of air...keep pumping and doing it until you start getting spits of fluid and air when you lift your finger...and soon enough the fluid pressure will get strong enough your finger can't hold it back...then put the bleeder screw back in and bleed normally...

Kind of a poor man's speed bleeder...be sure to keep the master full, or you'll be right back where you started...