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Noob brake question

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Alright, total noob question here. So I tried to bleed my front brake for the first time this weekend, and I’m not sure where I went wrong. I used the Motion Pro bleeder that’s basically just a check valve to keep air from getting back into the system. Bike is a 2004 KTM EXC 450, not that it matters but I couldn't figure out what forum to put it in so I ended up on the one where the bike does matter.

 
Anyways, I squeezed my brake lever, opened the bleeder valve, and continued to pump the brake lever, keeping the reservoir topped off with fresh fluid. However, I kept getting air bubbles in the motion pro bleeder, so I resorted to the old fashioned way of squeezing the lever, opening the valve, closing the valve, and re-squeezing the lever and repeating. Doing it that way, I couldn’t get the lever to give any resistance. I had to squeeze like 5 times with the bleeder closed to finally get pressure, then bleed it and repeat. So I finally got to a point I was fairly sure I got all air out of the system. Now, after everything is put back together, I still feel like I have to prime the brake, squeezing several times before it gets hard, and even when it does it’s nowhere as firm as I think it should be. I can pretty much pull it all the way in still.
 
I feel like I have to be doing something wrong here… Any tips?

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Alright, total noob question here. So I tried to bleed my front brake for the first time this weekend, and I’m not sure where I went wrong. I used the Motion Pro bleeder that’s basically just a check valve to keep air from getting back into the system. Bike is a 2004 KTM EXC 450, not that it matters but I couldn't figure out what forum to put it in so I ended up on the one where the bike does matter.

 
Anyways, I squeezed my brake lever, opened the bleeder valve, and continued to pump the brake lever, keeping the reservoir topped off with fresh fluid. However, I kept getting air bubbles in the motion pro bleeder, so I resorted to the old fashioned way of squeezing the lever, opening the valve, closing the valve, and re-squeezing the lever and repeating. Doing it that way, I couldn’t get the lever to give any resistance. I had to squeeze like 5 times with the bleeder closed to finally get pressure, then bleed it and repeat. So I finally got to a point I was fairly sure I got all air out of the system. Now, after everything is put back together, I still feel like I have to prime the brake, squeezing several times before it gets hard, and even when it does it’s nowhere as firm as I think it should be. I can pretty much pull it all the way in still.
 
I feel like I have to be doing something wrong here… Any tips?

 

You probably have air pocket somewhere up near the master cylinder, Im not big on breaking the banjo bolt, so might try removing caliper or wheel and squeese the shoes , so pistons go all the way back in, revesre bleed, this should have air bubbles coming out of the master cylinder, you may want to reduce the fluid level in the master, cause it will definitely rise as you press the pistons in.

 

 

 

any way that might be worth a shot, afterwards you might zip tie the brake lever under pressure to the grip and leave over night.

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You probably have air pocket somewhere up near the master cylinder, Im not big on breaking the banjo bolt, so might try removing caliper or wheel and squeese the shoes , so pistons go all the way back in, revesre bleed, this should have air bubbles coming out of the master cylinder, you may want to reduce the fluid level in the master, cause it will definitely rise as you press the pistons in.

 

 

 

any way that might be worth a shot, afterwards you might zip tie the brake lever under pressure to the grip and leave over night.

Alright cool. So basically I just didn't do a good job of bleeding it? Perfectly possible, I was a little more rushed than I should have been. Could I just continue bleeding normally instead of messing with the caliper? I was trying to swap out for new brake fluid anyways, but once I started having problems I gave up on that.

 

What would zip tying the lever to the grip overnight accomplish?

Another concern is how air was getting into the motion pro and possibly into the system in the first place. Could it be getting in through the threads of the bleeder bolt? Any other thoughts?

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Alright cool. So basically I just didn't do a good job of bleeding it? Perfectly possible, I was a little more rushed than I should have been. Could I just continue bleeding normally instead of messing with the caliper? I was trying to swap out for new brake fluid anyways, but once I started having problems I gave up on that.

 

What would zip tying the lever to the grip overnight accomplish?

Another concern is how air was getting into the motion pro and possibly into the system in the first place. Could it be getting in through the threads of the bleeder bolt? Any other thoughts?

The other trick I've tried which is successful & tried by others is that you need to unbolt your brake lever & master cylinder assembly from the bars & hang them as high as possible with the brake line vertical. You need to tap the brake line from bottom to the master cylinder working from brake slave cylinder to the master cylinder & then leave overnight. The theory behind this is that any air bubbles will work their way to the highest point overnight. The earlier 2009 KTM's apparently had an issue with losing prime over several days & this seemed to fix it for a long time.

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The other trick I've tried which is successful & tried by others is that you need to unbolt your brake lever & master cylinder assembly from the bars & hang them as high as possible with the brake line vertical. You need to tap the brake line from bottom to the master cylinder working from brake slave cylinder to the master cylinder & then leave overnight. The theory behind this is that any air bubbles will work their way to the highest point overnight. The earlier 2009 KTM's apparently had an issue with losing prime over several days & this seemed to fix it for a long time.

Great info thanks!

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Alright cool. So basically I just didn't do a good job of bleeding it? Perfectly possible, I was a little more rushed than I should have been. Could I just continue bleeding normally instead of messing with the caliper? I was trying to swap out for new brake fluid anyways, but once I started having problems I gave up on that.

 

What would zip tying the lever to the grip overnight accomplish?

Another concern is how air was getting into the motion pro and possibly into the system in the first place. Could it be getting in through the threads of the bleeder bolt? Any other thoughts?

Just do it the manual way and avoid the gadgets in the future,, the zip tie just keeps the system pressurized over night, hopefully forcing any air out .

Edited by Spud786

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Pressure bleed it from the master cylinder banjo bolt (repeat several times) till it builds pressure.

 

Then pressure bleed it from the bleeder bolt a few times, "the old fashion way".

 

Now gravity bleed it (filling the reservoir at least once), done. 

Edited by Throttle5

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Gotta push the pads in all the way and compress the piston. ....there is air behind it

 

If you use the bleeder, be sure to put plumbers tape on the threads, or air will suck past the threads.

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my front brakes magically loose pressure every so often. I will also use the zip-tie method over night and seems to cure it untill the next time....

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