audilad9 Posted July 18, 2015 Report Share Posted July 18, 2015 Hello all, new on here, and hope someone can help My bike is a 2010 250 pro. The problem appears to arise after a bit of time say 10 minutes of riding, I hear the rear brake start to squeal as it begins to bind and the pedal hard. I obviously stop at this point and the brake becomes solid, locking the wheel, the disc hot to the touch. The rear pads appear ok, I have had them out to check and clean, caliper pistons appear free enough. My guess is in the pedal/ master cylinder, it goes solid, ie no pedal travel. Fluid level is ok and was working fine before with nothing done to upset anything. Any ideas anyone ? Thanks. Quote Link to comment Share on other sites More sharing options...
cheesepreetza Posted July 18, 2015 Report Share Posted July 18, 2015 Flush the fluid out with what ever is on the cap or on your manual. Complete flush, it has boiled over at least once or has crud or water in the line. keep going until its clear, (motul has a slight gold tinge) Had this exact issue happen to my ktm 150, flushing it did the trick, i now flush the fluid about 3 times a year for what it costs, brakes work much better. If your rear brake fluid was dirty i would imagine the front would need to too. Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted July 18, 2015 Report Share Posted July 18, 2015 (edited) Normaly something like 2% of water will get into the system each year. And this dramaticcally lowers the boiling point. So clearing the system once in a wile is easy, way better for the system, and not expensive. Offcoarse something else could be off in your case. Edited July 18, 2015 by crazybond700 Quote Link to comment Share on other sites More sharing options...
eddie1 Posted July 18, 2015 Report Share Posted July 18, 2015 I am fairly certain that you do not have enough free play at your brake lever. You need to adjust the rod to give more play. What is happening at the moment is that the brake is always slightly on. When the bike is cold the pads do not quite touch the disc but once you start to use it the pads and disc warm up and the pads start to bind. Once this happens it is only a short time before the brake will fully lock the wheel until it cools down again. 1 Quote Link to comment Share on other sites More sharing options...
audilad9 Posted July 18, 2015 Author Report Share Posted July 18, 2015 Thanks so much for the replies guys. I shall give it a bleed through tomorrow, the fluid sounds like a probable cause as I have been power washing it quite vigorously lately and the pedal travel was fine before, its not been adjusted and pads are well clear of disc at cold. I'll report tomorrow how it goes. Thanks Quote Link to comment Share on other sites More sharing options...
crazybond700 Posted July 18, 2015 Report Share Posted July 18, 2015 Keep in mind that altough the boiling point is lowered with old brake fluid, it still only boils when the system gets hot, so something is causing too much friction. Quote Link to comment Share on other sites More sharing options...
audilad9 Posted July 18, 2015 Author Report Share Posted July 18, 2015 Possibly a lot of riding around on the back wheel covering the brake I will look at all possible causes and report back. Thanks Quote Link to comment Share on other sites More sharing options...
gii Posted July 18, 2015 Report Share Posted July 18, 2015 Your problem is almost certainly in the pedal / master cylinder set up Either the pedal does not have sufficient free play to allow the piston in the master cylinder to return fully and open the port to the reservoir, or dirt has built up in the master cylinder around the push rod again stopping the piston from returning fully. Bleeding the system may alleviate the fault as working the pedal through its full range might 'encourage' the master cylinder piston to return properly You'd have to be pretty tricky to introduce water into the sealed system via a pressure washer so don't blame yourself there 1 Quote Link to comment Share on other sites More sharing options...
audilad9 Posted July 18, 2015 Author Report Share Posted July 18, 2015 Thanks gii I should have mentioned that leaving it to cool down for say five minutes, the pedal has good travel again and works perfectly for a while. I shall give a thorough strip, clean and inspection now that I have some ideas of things to look for. Cheers Quote Link to comment Share on other sites More sharing options...
gii Posted July 18, 2015 Report Share Posted July 18, 2015 Yep, that reinforces my opinion. When it all cools down and contracts, everything's fine. There should be no pressure in the system when your foot is off the pedal because the open port in the master cylinder to the reservoir vents off the pressure.. Take the pedal off, clean the master cylinder where the push rod enters then re fit the pedal and set it up with a little bit of clearance, the pedal may be lower than you've got used to but you can adapt to that. If you bleed the system and get inky fluid out then a seal is degrading, but that's a different problem that will eventually lead to a leak not a brake stuck on. Quote Link to comment Share on other sites More sharing options...
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