Two Stroke Motocross

Two Stroke Motocross Forum => Technical => Topic started by: jamez-0001 on October 26, 2013, 08:29:28 PM

Title: KX250 front brake problem
Post by: jamez-0001 on October 26, 2013, 08:29:28 PM
Hi,

Got a bit of a bizarre problem - maybe someone can help?

KX250 1997 with nissin twin piston brake caliper and master cylinder. Front brake very weak. When pushing the bike and applying brake, it won't stop completely. Have bled system and lever feels quite firm and doesn't loose firmness when held down. Pistons are moving freely. Pad guide pin is a bit grooved. Have cleaned brake disc thoroughly and put a set of new pads in. All to no avail. The really odd thing is that after washing the bike down with water, the brake grabs much better! Can't get my head round it  ::)
Title: KX250 front brake problem
Post by: evo550 on October 26, 2013, 11:07:14 PM
Something on the pads?
Title: KX250 front brake problem
Post by: Stusmoke on October 26, 2013, 11:57:20 PM
Quote from: evo550 on October 27, 2013, 06:07:14 AM
Something on the pads?

x2 go somewhere you can ride in a straight line, ride along in first gear and drag the brakes until it gets quite hot. Hopefully that will evaporate whatever is on them. Sometimes if you spray WD-40 on the bike somewhere, it can mist over and settle on the rotors or something like that. I find degreaser is just as bad so if you were washing your axles with that be careful.
Title: KX250 front brake problem
Post by: eprovenzano on October 27, 2013, 01:44:26 PM
Quote from: evo550 on October 27, 2013, 06:07:14 AM
Something on the pads?

I agree...  (I can't believe I'm tying this :-[ ) Try Stu's method and let us know what happens... 
Title: KX250 front brake problem
Post by: SachsGS on October 27, 2013, 02:51:01 PM
The brake caliper is typically mounted on pins which allow it to "float" and position itself on the disc. Make sure it's not seized. As well, make sure the disc itself is not warped or heavily glazed.
Title: KX250 front brake problem
Post by: Stusmoke on October 28, 2013, 12:31:03 AM
Quote from: eprovenzano on October 27, 2013, 08:44:26 PM
Quote from: evo550 on October 27, 2013, 06:07:14 AM
Something on the pads?

I agree...  (I can't believe I'm tying this :-[ ) Try Stu's method and let us know what happens... 

Happy day! Don't do it often though unless you really like replacing brake pads ;D
Title: KX250 front brake problem
Post by: evo550 on October 28, 2013, 05:14:13 AM
Most new pads need to be "broken in", this process is usually written on the manufacturer packaging somewhere (that we never read) which could help.
Title: KX250 front brake problem
Post by: Stusmoke on October 28, 2013, 05:22:42 AM
Quote from: evo550 on October 28, 2013, 12:14:13 PM
Most new pads need to be "broken in", this process is usually written on the manufacturer packaging somewhere (that we never read) which could help.


Good thought. Fresh rotors need a little break in too I'm told. Running a KTM means you never have to buy another one  ;)
Title: KX250 front brake problem
Post by: jamez-0001 on October 30, 2013, 09:27:53 PM
Cheers for the tips guys; I'll try these suggestions on Saturday!
Title: KX250 front brake problem
Post by: jamez-0001 on November 08, 2013, 06:49:10 PM
Got brakes working a lot better! I followed the suggestions and rode the bike slowly with the front brake on. Seems to have done the trick! I think the disc was glazed over, as the old pads didn't bite either. I remember cleaning disc with electro contact cleaner at some point, which maybe didn't help. Seems to have worked a treat - cheers guys, much appreciated!
Title: KX250 front brake problem
Post by: Stusmoke on November 10, 2013, 12:36:04 AM
not a worry mate glad its sorted. Just don't do it often cos it eats pads.