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Just bought this bike for 500. Front brakes dont work. The lever isnt limp. It has a small amount of resistance but doesnt get harder if i pump the brakes and can push the cylinder. Thought bleeding the brakes would be the first step. But it wont build any pressure. Any tips?
81cx500 custom
 

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Rebuild the caliper and replace the master cylinder. Many here have been happy with cheap ones from ebay. If the brake line looks to be original replace it too and preferably with a ss one.
 

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1981 CX500D, 1976 RD400C, 1972 H2 750
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Disconnect brake line from master cyl, fill master cyl, place finger over outlet port and pump master cly....repeat till it pushes your finger off, connect line now it should bleed normal.You will have to remove your finger from the port to get the trapped air in master to escape.
 

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Or just tickle the lever until the air stops rising from the bottom of the master and then start to bleed.
 

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The hoses can fail internally but look fine from the outside. Disconnect the line at the caliper and pump the lever. If you don't get a squirt each time you move the lever, change the hose(s). Now when it comes time to bleed the system., cover any painted parts with a towel, fill the reservoir. Now take the assembly off the handlebar and hold it vertical so the trapped air bubbles can rise up through the banjo fitting and make the 90 degree turn into the reservoir. Pump the lever a bit in this position, then reattach to the handlebar. If you don't do that chance are it will take you all day.
 

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It won't take all day without finger bleeding. Try tickling the lever just enough to make the brake light switch click.

I never finger bleed.

I changed a master cylinder in the last week without even getting air at the bleed nipples. Took less than a few minutes to just pump the fluid in the lines through.

Of course, it may now be too late for this approach to work.
 

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'84 CX650E that is evolving into a GL500
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Of course if you use a vacuum pump you don't have to worry about any of that.

Welcome to the forum. Please add your location and your bike's model and model year to your profile so that you don't have to remember to tell us every time and we don't have to keep asking when you forget (see Forum Settings link in my signature).

And welcome to the world of antique vehicle ownership (they own us, not the other way around). Your bike is about 4 decades old and may or may not have had all of the maintenance necessary to keep it safe & reliable so it is highly recommended to download the Factory Shop Manual for your model (available through the CX Wiki - link in my signature) and go through all of the service procedures, regardless of whether your bike has reached the specified mileage.
I also recommend looking on all rubber parts with suspicion because rubber does not age gracefully. Check the date codes on your tires and replace them if they are over 5 years old no matter how good they look & feel (old rubber simply cannot flow around the irregularities in the asphalt well enough to grip, especially if it is cool or wet). If your bike still has the original rubber brake line(s) (should be replaced every 2 or 3 fluid changes = 5 or 6 years) I recommend shopping for modern stainless braided ones (they last practically forever and double the life of the fluid). And don't forget things like the rad hoses and the boot between the engine and swingarm (they can crack on the bottom where you don't see it).
 

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Just bought this bike for 500. Front brakes dont work. The lever isnt limp. It has a small amount of resistance but doesnt get harder if i pump the brakes and can push the cylinder. Thought bleeding the brakes would be the first step. But it wont build any pressure. Any tips?
81cx500 custom
You need to use a vacuum pump. I have a 1981 CX500 Deluxe and messed with all kinds of methods for a week, then purchased a vacuum pump and in 30 seconds front brake pressured up.
 

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Certainly there are several methods that will work effectively, vac pump being one. Marks vertical method also is effective. I have a vac pump in my toolbox as it is useful for many tasks.
 
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