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2010 YZ250 brake issue

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Recently got my YZ250 and so far I really like it. One thing I am having a problem with is the front brake. 

 

It seems to have lots of "play" compared to other bikes and worse yet while riding and using the brake you can feel it pulse- almost like the rotor is warped(its not). 

 

In trying to troubleshoot it(while stationary) I get a solid amount of pressure until a certain spot in the disc and then the lever goes to the handlebar. Let out and it is nice and solid again when pulled. 

 

I have Braking rotors with brand new pads, new fluid, and stick caliper/master.   Should I get new rotors?  Could one part my rotor really be thinner than the rest?

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Do you have the stock rotor to put on and see? Sure you don't have an air bubble?

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I don't ha e the stock rotor. And I'm pretty sure I don't have a bubble. I think I'll just order new rotors and call it good. Not sure what else to try.

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Are the brakes on your bikes pretty stout/ touchy?  My Honda had great brakes and I can't seem to get the same feeling out of this bike. 

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I have found that the front brakes on YZ's feel different from all the Honda's and my Italian bikes for that matter. There is a possibility that you have a glazed or even creosote patch on the rotor that was not properly cleaned off. Before you buy rotors, get some brake clean and give it a good cleaning on both sides. Might even try new pads at the same time or pull them out and give them a cleaning, sanding and reinstall.

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Or try the honda master cylinder and see if that helps. I found it helped mine with more stout feeling. Lots of threads on here about it. I got one off ebay for about $30 from an 09 CRF250.

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My pads are brand new, have about 10 laps at my track. 

 

It sounds fickle but being comfy on a bike is important. I like everything except the clutch, bars, brakes on this bike. Going to get some risers to see if that helps me with the bars.  Clutch can be made better with x springs and hopefully rotors fix the brake. I will try to wipe them down just to make sure but I think they are nice and clean. 

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I put the X springs on my clutch and I like it. Still seems to be plenty strong.

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My pads are brand new, have about 10 laps at my track. 

 

It sounds fickle but being comfy on a bike is important. I like everything except the clutch, bars, brakes on this bike. Going to get some risers to see if that helps me with the bars.  Clutch can be made better with x springs and hopefully rotors fix the brake. I will try to wipe them down just to make sure but I think they are nice and clean.

Pads might have had transferred material from rotors. Clean them off and drag across flat surfaces sandpaper also to be sure. It's the same theory of your brakes on a car when you just get new pads put on, you need to "set" them to the rotor again.

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In trying to troubleshoot it(while stationary) I get a solid amount of pressure until a certain spot in the disc and then the lever goes to the handlebar. Let out and it is nice and solid again when pulled.

That right there tell me the rotor is warped...or the hub is bent. Bent hub is very rare but recently a buddy of mine found his front hub bent and it caused the warped rotor scenario you describe above. Take the rotor off the hub and it would spring back and NOT measure warped.

But generally a warped rotor or bent hub will do EXACTLY what you described.

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The rotor lays flat so I don't think it's warped. Going to order new rotors and hope that's the fix. Riding today was a little dangerous. ImageUploadedByThumper Talk1461456963.391533.jpg

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My 2005 needs about a 1/2" of lever movement before it starts to engage, but then it is smooth as silk. Not an adjustment issue. Bled very well as far as I can tell. Just has to move a little before it engages (new pads).

 

EDIT: 1/2 inch, not 1/2 of lever movement.

Edited by LSHD
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Good news: front rotor was replaced and appears to have corrected the problem. Brake lever does not seem as firm as I expected but I guess I'm learning there really is a difference vs Honda brakes. Front brake is safe now.

Bad news: rear rotor was replaced and now it makes contact with the pin that holds the rear brake pads in the caliper. Disc is physically the same size, pin even has a groove for the rotor but makes a horrible clanking sound. Anyone had this issue before?

ImageUploadedByThumper Talk1461923449.578367.jpg

ImageUploadedByThumper Talk1461923516.101798.jpg

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My 2005 needs about a 1/2" of lever movement before it starts to engage, but then it is smooth as silk.

 

There is a thread (around here somewhere) that showed the differences between the Honda and Yamaha plunger in the master cylinder.

 

The CR has a very short "nose" on the plunger, while the YZ's was about 4mm longer. Therefore, when the lever was moved, the ports in the CR's master cylinder were uncovered much sooner then the ports in the YZ, resulting in a Right Now feel at the lever. This is why the YZ has more play in the lever before the brakes actually engage; the plunger has to move further before the ports are opened.

 

Some people have put a CR plunger in their YZ master cylinder, but there are 2 problems;

- Not all CR plungers fit, and no one seems to know what years will swap.

- The cost of a Honda MC rebuild kit (the only way to purchase a plunger) is more than most entire master cylinders available on eBay.

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Thanks, CaptDan, for the info on the YZ. I always felt is was totally normal for the YZ brake to have more uptake, but had no idea why.

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Im thinking that the bracket is just super sloppy. I can move the caliper/bracket forward and it doesn't make any noise.  Ill tear it apart again to see how to fix this, may need a new bracket. 

 

The disc is just a tiny bit larger, about 1-2mm. 90% sure its the bracket after looking at it again. The slot on the swingarm and the slot on the bracket need to have tighter tolerances it seems. 

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