125-200cc WR 125 Front Brake Problem

Hi guys, looking for some help with my front brake. Went for a ride today and on a long descent the front brake overheated and went spongy. I waited for it to cool but now the front brake lever is solid and won't compress at all.

It's not holding the brakes on - the front wheel spins freely and the pads aren't dragging on the disc.

I have tried bleeding the brakes at the caliper. After pulling some initial fluid through, no more fluid is coming through.

I also tried squeezing the lever whilst the caliper bleed nipple was cracked open - nothing, won't compress at all.

Feels like there could be a problem with the master cylinder or a blockage between the master cylinder and the caliper. Does anyone have any suggestions?

Update: Disconnected the brake line at the master cylinder. The lever moved freely. I reconnected the brake line and pumped the lever. Pressure built up until the lever was rock hard again. Still no action on the caliper though.

So I disconnected the brake line at the caliper. The lever was still solid and no fluid flowed out of the line no matter how hard I squeezed.

So the blockage is in the brake line. I think I read somewhere about dirty fluid near the caliper being forced up into the brake line when the brakes overheat.

What's the fix? If I keep squeezing the lever can I force the dirty brake fluid out the end of the line? Don't want to damage my master cylinder though.

Why not disconnect both ends and blow it out with air?

Thanks. Will give it a go. If I can't clear it somehow I think the best way forward is a new brake line

Found a new line for a 2012 WR 250. Anyone know if it will also fit the 2012 WR 125?

Sometimes a brake line-liner will separate due to age, injury or both and collapse causing a partial or complete blockage.

125 & 250/300 seem like theyre the same but don't quote me

Would more likely be a stuck caliper or related , don't reckon it's a line.

Thanks for the replies everyone.

I did some more investigating last night. Took a spool of lockwire I had lying around and carefully fed the wire into the brake line starting from the master cylinder end. It went in almost to the other end and then stopped. Wouldn't go any further.

So I tried feeding the wire in from the caliper end of the brake line instead. Immediately found the problem. The caliper end of the brake line was completely blocked up. Took a lot of effort but I was finally able to force the wire through the blockage and up into the brake line.

Sprayed some brake cleaner on the wire and ran it in and out of the line until it was moving freely. I will try flushing the line through but I am worried that there may still be remnants of the blockage in the line that could give me another problem. So will put a new line on to be safe.

I would really like to understand exactly what caused the blockage. As I mentioned the brakes overheated and the lever came back to the bar (even though I am careful about changing my brake fluid regularly to keep it fresh). It almost looked like the end of the line was fused closed.