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Front brake problem

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Ok so this is the story, I replaced the front brake on my 12 kx250f to an oversized rotor. Ever since the front wheel didn't spin so freely. Last week, 30 engine hours later, I loaded up the bike and I secured the front brake. About 10 min later I noticed that although the front lever is applied the front wheel keeps moving around. I looked and I saw some brake fluid on the brake lever. Today I tried to bleed the brake and now the lever has no effect on the brake and the wheel still does not spin right.

**update, now the brake seems to work fine, except that there is still a drag in the wheel. If I take the caliper out the wheel can spin very freely. I'm a bit timid that it will stop working in the middle of riding because of the drag the front brake will over hit.

Idk what to do, please help.

Gill

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Too much drag on the rotor means the pistons aren't receding into the caliper.  Did you replace the pads, too?  The difference in thickness of the new rotor and/or pads might be causing the drag if the rims of the pistons are dirty.  You should be able to see build up just by visually inspecting the rims of the pistons.

 

It's not hard to service the caliper.  Replacing the seals is easy and cleaning the pistons is, too.  I spin the pistons on the end of a drill by wrapping a small grinding stone with a strip of inner tube and sliding the piston over it, then use progressively fine sandpaper to give them a mirror finish.  Works great for me.

 

Fluid on the lever means the system leaked somehow or you just spilled fluid in the bleeding process.  Could be the MC cover or plunger or banjo bolt.  Easiest if you can determine where the fluid came from.  You can always replace the copper washers, tighten the cap or rebuild the plunger.  All easy and relatively cheap.

 

Having recently experienced front-brake lockup myself, I would say it's worth making sure things are perfect.  Sounds like that's what you are trying to do.  Good for you.  Keep us posted.

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I re-installed the original rotor, the problem is still there.

so I pried open the pads with a screwdriver and then the wheel spanned freely. But once I applied the brake lever the pistons did not recede back fully.

Ill try to clean them and I'll give you guys an update.

Dragon67 thanks very much for an always prompt and on point response !!

Gill

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Here is the deal. When you use the replacement "HOLDER-ASSY,FRONT CALIPER" you need to modify it. There is clearly a binding issue if the wheel spins freely without it installed. My suggestion would be to use some type of spacer, washer, ect. On the bolts to the mounting bracket. If that doesn't work go the opposite route and take a small bit of material off, at a time, of the "HOLDER-ASSY,FRONT CALIPER" until it spins freely I've done this before so I know it works.

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also check your rims for trueness, and only use  stock roters on 11- 14 kx250f

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also check your rims for trueness, and only use  stock roters on 11- 14 kx250f

RIM has nothing to do with it the rotor bolts to the hub , i have a galfer setup and it works fine on a 14 the pads will lightly rub the rotor but will spin freely, i guess any holder can be machined slighly off , maybe having to file some off or washering it depending, wouldnt suprise me with all the china made ones on ebay, the galfer is billet ,some of that stuff on ebay looks cast, 

Edited by fgrote

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