• Welcome to the Two Wheeled Texans community! Feel free to hang out and lurk as long as you like. However, we would like to encourage you to register so that you can join the community and use the numerous features on the site. After registering, don't forget to post up an introduction!

Brake bleed help

Forums New posts
MaxxTraxx

MaxxTraxx

0
Joined
Jul 17, 2006
Messages
1,608
Reaction score
151
Location
Conroe, Tx
First Name
Bryan
Sorry for the long post….

I’m hitting a road block and need a little guidance from the collective wisdom.
81 CX500C
I installed a new SS front brake line due to the old line having no fluid passage thru it.

With the MC full of fluid, I see a minute amount of fluid movement and feel some pressure on my finger at the MC port. (Where the banjo threads into) Using a syringe I added fluid to the brake line until I got fluid flow from the caliper bleeder. At that point I connected the line at the MC and squeezed the brake lever. Very light lever and very minimal fluid movement. I either have a MC problem, or just a ridiculous amount of trapped air. I’m frustrated and not sure what to check. I have the brake lever zip-ty the lever closed and trying to let it gravity bleed.

 
I've had good luck pushing fluid up to the mc from the caliper bleeder. You'll need a big syringe and a little piece of tubing. Push from the bottom until the mc reservoir is about full. Then empty it and repeat until you have no more air in the system.
 
You need a wrench on the caliper bleed screw. Tighten the bleed screw on the caliper, squeeze and hold the brake lever, loosen the bleed screw for a second or two and then tighten it back up, then release the brake lever. Then repeat that until no more air comes out or you get tired of doing it.

Side note, pinning the brake lever to the grip won't let anything gravity bleed as you have closed off the master cylinder to the line. If this wasn't the case, then every time you pulled the brake lever in, instead of pressure pushing the pads to the rotor, you would just have an open system and nothing would push the pads out.
 
How are you convinced the master cylinder is working properly and the problem was the brake line?
If you're only feeling a small bit of pressure at the outlet port the m/c may need a reseal.
 
Based on what you described, I have to agree with dukey33, you may not need a seal kit, but I would be removing the master cylinder plunger and seals and checking nothing is damaged and no dirt is blocking the small holes between the reservoir and the master cylinder plunger..
 
It can take some time when you start with a dry line like you have. Air bubbles act as a lock and hold the fluid back from reaching the caliper. You have gotten some really good advice so far. Gravity bleed is good if you have the time, but as DFW Warrior says you ain't doing any gravity bleeding with the lever zip tied back.

The forced reverse bleed with a syringe from the bottom up, like RG said, is the quickest way to fill a dry brake line/dry system. You need to make sure there is no lever pressure at all on the master cylinder or else the fluid will not be able to move up and out of the master cylinder. Take off the lever is the easiest thing to do if you are not sure. You also have to make sure you are not introducing more air into the system as you inject the fluid up from the bleed screw.

If you do the traditional pump/crack screw/close screw/release lever method, hard taps on the line with a wrench or screw driver will help release bubbles or air locks.
 
dukey33 said:
How are you convinced the master cylinder is working properly and the problem was the brake line?
If you're only feeling a small bit of pressure at the outlet port the m/c may need a reseal.
Click to expand...
Im not 100% on the MC, but I do get pressure at the port, albeit a small amount. A reseal is more than likely gonna happen due to the age of the bike.

With the old brake line off the bike I can not pass air thru the line from my air compressor.
 
Pulled the MC apart and it’s gunked up and makes it hard to build pressure. Rebuild kit ordered.
 

Attachments

  • image.jpg
    image.jpg
    243 KB · Views: 104
Kids, this is why we change brake fluid every 2-3 years. Needs to be done even if we aren't riding the bikes (or cars, whatever). The fluid itself breaks down and causes issues like needing to buy new brake lines, which cost a lot more than a little brake fluid.

You also need to disassemble the caliper, since it is full of the same crap. And if the front is full of that, the rear almost certainly is, too. The good news is, there's a chance all your problems are just the presence of the broken down brake fluid, and all the seals and metal bits are fine. I'd pull it apart and inspect everything before ordering parts. Be gentle with the seals.

Clean everything with denatured alcohol. It's chemically compatible with the seals. Rinse with water, rinse again with alcohol to get the water off, and blow the alcohol off with compressed air (it evaporates faster than water). Carb cleaner and brake cleaner will damage the EPDM rubber parts. Be sure to flush out the new brake line to get out any gunk that you've gotten into it.

Lube the seals, pistons and other parts with brake fluid when reassembling. Wear nitrile gloves to keep the brake fluid off your hands. Once everything is fully assembled and sealed up, you can rinse brake fluid off the outside with clear water. No need for any other solvents.

When putting it back together, I've had good luck getting those last little bubbles out of the m/c by leaving the bleed screw closed and just compressing a piston in the caliper to push the fluid backward (this is once everything is filled with all-new clean fluid).
 
Drum rear. But yeah, caliper is all apart to and it’s gunky. This was grandpas bike snd it has sat at least 4yrs. It only has like 9400 miles on it at any rate. Wasn’t ridden a ton. Once the brakes are ironed out and I replace the 13yr old tires I’ll. E able to ride it safely.
 
saltydog said:
The gas tank and carbs are probably in similar shape. Flush and replace the fork fluid too.
Click to expand...
It runs great. Everything works except the front brake. It was stored indoors or in a climate controlled garage it’s whole life.
 
You're lucky the brakes are all Grampa let go. It will be nice having front brakes that work again. Most old bikes around here have weathered outside and are too expensive to road ready.
 
saltydog said:
You're lucky the brakes are all Grampa let go. It will be nice having front brakes that work again. Most old bikes around here have weathered outside and are too expensive to road ready.
Click to expand...
Yep. It will be great to get out and really ride it again. Last time I rode it I was 16.
 

Attachments

  • AE381CE0-974D-492F-BEA1-ADCC07FA30E2.jpeg
    AE381CE0-974D-492F-BEA1-ADCC07FA30E2.jpeg
    579.8 KB · Views: 91
Great to be riding again, just hope you can stop when ya want. Salty Dog's advice and tank clean, carbs, fuel lines, fork fluid is spot on. If it runs good, still do the forks. Does not matter where its stored some parts are toast after sitting a long time. Plop an inline fuel filter in there too with the new lines as the tank may take a long time to clean up. Nice bike though, and they last a long time when cared for.
 
Im on the hunt for some upgraded fork spings. I need to get it out and put some miles on it though to help shake it down. Make sure it dosent develop a coolant leak or some other age related malady from being stored.
 
I recently installed SS brake lines up front on my MT07. Try as I might, I couldn't seem to get the lever feel to firm up to expectation (most of my hydraulic brake experience has been automotive). ~20 miles into the next ride, she had self bled the little air that was left. Perfect, firm engagement now. I've heard of others who say this process works during track bike trailer transport, as well. Seems similar to the "tap the lines" method mentioned above. May try that 1st, next time :)
 
I often bleed the system as best I can, then pull the brake lever on hard, fit a cable tie to keep the system pressurised, turn the bars to the left to get the reservoir at the highest point and leave the bike over night. By pressurizing the system any air bubbles get compressed and become smaller, making it easier for them to rise and then just leaving the system pressurized overnight allows the small bubbles to rise to the reservoir. In the morning I remove the cable tie and usually have a great firm brake lever..
 
You must log in or register to reply here.
Back
Top