2017 yzf 250 front brake spongy

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8/29/2017 9:45 AM

I realise this question has probably been asked over and over I just can't seem to fix the problem!!

I had a big crash about 2 months ago and the bike landed on the right side bending the front brake lever up, snapping the throttle tube but more importantly loosing all pressure on the front brake.
The lever just comes straight into the bars/grip.

The bike has only done about 20 hours.

I have bled the brake time and time again but can't seem to get any pressure

Any ideas before I go insane??

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8/29/2017 10:46 AM

The crash may have damaged the internals of the master cylinder. Rebuild or replace the unit. Also use either gravity to do a reverse bleed from the caliber to the master or us a vaccum bleeder. These little masters don't move much fluid under ideal conditions and attempting to bleed by pumping and will be almost usless as there is just not enough fluid moving.

Paw Paw

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8/29/2017 1:22 PM

What Paw Paw said.

Id also add, check the banjo bold up by the master cylinder. I crashed and my brake line got twisted and it cause it to come lose and I was getting a little bit of air in there.

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8/29/2017 1:45 PM

Cheers guys, I've checked all bolts etc looks like I'll try a master cylinder rebuild kit

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8/30/2017 9:06 AM

Could have tweaked the cylinder itself too.

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2009 Kawasaki KX450F
2009 Kawasaki KX250F
2002 Suzuki GSXR 600

8/30/2017 9:46 AM

ronniemacwannabie wrote:

I realise this question has probably been asked over and over I just can't seem to fix the problem!!

I had a big crash about 2 months ago and the bike landed on the right side bending the front brake lever up, snapping the throttle tube but more importantly loosing all pressure on the front brake.
The lever just comes straight into the bars/grip.

The bike has only done about 20 hours.

I have bled the brake time and time again but can't seem to get any pressure

Any ideas before I go insane??

Ride the bike with no front brake for a new laps and when you get back to the pits it will have enough pressure to start bleeding it.



I had the same problem as you.

I let my GF ride my race bike on the trails (2016 YZ250F) because she was having trouble on the 125 in the deep sand. Well needless to say she smacked a tree and it pinched the stock brake line pouring all the fluid out.

I ordered a streamline steel brake line and took it with me to the track figuring I would just swap it before practice.

I tried EVERYTHING. Even sucking brake fluid into my mouth through a hose on the bleeder trying to get some pressure. Nothing worked.

I got pissed and said screw it. I already paid to practice so I'll just ride a moto with no front brake.

Came back to the pits and it had a little feel in the lever. I was able to bleed it after that and get good feel back.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

8/30/2017 9:47 AM
Edited Date/Time: 8/30/2017 9:48 AM

To add to that last post. If you have the cap off the master you will be able to see that there is a large air bubble in the diaphragm. This is the problem. With the air in that diaphragm its not creating any pressure.

Riding the bike was enough to shake all that air out for me.

A vacuum bleeder would also work I imagine.

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Race Bike: 2018 KTM 350SXF

Other Bikes: 1985 CR80R, 1990 CR250R, 1998 PW80, Specialized Fuse Comp 29.

Sold: 2016 YZ250F, 2012 CRF250R

9/2/2017 9:13 AM

I haven't read all the posts - probably mentioned already - If bleeding and leaving a rubberband pulling in your front brake on it overnight won't work you'll need to rebuild your master cylinder - then bleed and rubberband

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