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i have a 2004 crf250r that i just recently bought. when i got the bike the owner before me just put on new rear brake pads...well the brakes weren't working that good so i went to bleed them and when i did i never got it to work again. a little bit of fluid comes out but it doesn't build pressure. whats going on?? any help would be greatly appreciated! thanks!

Maybe a hole in the brake line??? Are they adjusted properly?

You might want to check out the master cylinder also, and make sure everything is okay in the caliper.

Best of luck.

viper1891 wrote:i have a 2004 crf250r that i just recently bought. when i got the bike the owner before me just put on new rear brake pads...well the brakes weren't working that good so i went to bleed them and when i did i never got it to work again. a little bit of fluid comes out but it doesn't build pressure. whats going on?? any help would be greatly appreciated! thanks!

Sounds like you may have a good bit of air in there.
Try this:
1) Make sure you have enough brake fluid. Add if needed.
2) Pump up the rear brake pedal to ensure you can at least build some kind of pressure.
3) Have an assistant hold the brake pedal down while you crack the bleeder valve. Tighten the bleeder valve after the pedal has dropped *before* your assistant takes his foot off it.
4) Recheck fluid amount. Add if needed, and repeat 2+3.

See if that helps - would be hard to imagine you have a faulty master cylinder, although it's not impossible. If the caliper is at fault, I'd think you'd see leaking fluid from somewhere.

What does the pedal feel like right now?

Monkeywrench wrote:

viper1891 wrote:i have a 2004 crf250r that i just recently bought. when i got the bike the owner before me just put on new rear brake pads...well the brakes weren't working that good so i went to bleed them and when i did i never got it to work again. a little bit of fluid comes out but it doesn't build pressure. whats going on?? any help would be greatly appreciated! thanks!

Sounds like you may have a good bit of air in there.
Try this:
1) Make sure you have enough brake fluid. Add if needed.
2) Pump up the rear brake pedal to ensure you can at least build some kind of pressure.
3) Have an assistant hold the brake pedal down while you crack the bleeder valve. Tighten the bleeder valve after the pedal has dropped *before* your assistant takes his foot off it.
4) Recheck fluid amount. Add if needed, and repeat 2+3.

See if that helps - would be hard to imagine you have a faulty master cylinder, although it's not impossible. If the caliper is at fault, I'd think you'd see leaking fluid from somewhere.

What does the pedal feel like right now?

the pedal has absolutley no pressure..ive checked the caliper and the master cylinder ( took it apart and put it back together) and nothing seems to be wrong. Nothing is leaking anywhere so im a bit confused

When you crack the bleeder screw, do you get any fluid as you bump the pedal?

Follow Monkey's advice until you get some fluid and your brake starts to pump up and then "reverse bleed" the rest of the air to get a tight feeling back in the brake. To do that you push the caliper in and pump the brakes back up and repeat three or four times. Once it pumps up you can also put some weight on the pedal and leave it overnight and air will make its way to the master cylinder.

If you accidently ran the master low while bleeding your brake - you introduced a lot of air into the system and your brake will act like you have described.

AS (~) shared a zip tie trick where you zip tie your front brake back overnight and it works. I've boiled the fluid flat tracking and my front got a little squishy - Did AS's trick and it fixed them right up.

i do get fluid coming through when i crack it, but not alot. the weird thing is that i have never gotten pressure once in the 4 hours i was working on it

Wow - maybe your brake line is damaged and won't let the fluid pass correctly. If the caliper moves in easily and you don't see any leaks then that's probably not your problem. Diaphram look ok? How far have you torn the system down?

Edit: Of course if you caliper is going in easily then the brake line is allowing fluid to pass...

i have torn it down completely, blew everything out and more. i dont think its the break line because nothing leaks and the brake did work before i tried to bleed it, it just didnt work very good. also, the piston is easy to move

so for anyone reading this thread. i have narrowed the problem down to the master cylinder. im not sure if there is anything missing or if it needs to be rebuilt. i could take it down to the local shop and have it fixed but that would cost a small fortune! lol. so if anyone has any advice or digrames it would be a world of help

thanks!

If you're sure it's the master cylinder, here's a link to the diagram and site you can order rebuild parts from:
http://www.another site.com/offroad/oem.php?make=HONDA&type=DIRT&model=CRF250R&year=2004&groupId=2806
Just double check your model & year - make sure I entered it right.

If you plan a rebuild, you might want to skim thru disassembly of it in the tech manual. Sometimes you need goofy special tools to open up things like that.

Something is sending my attention toward part #12 in that diagram... any chance the fluid isn't making its way thru the special oil bolt? Maybe dirt or particles clogged inside?? (either end -- front or back)...

If you disconnect the front oil bolt and put your thumb over the outlet and pump up the pedal, see if it builds pressure against your thumb (or pinky, index finger...)
If it does, I'd say you don't need a rebuild. Maybe try the same thing at the back end after hooking up the front. See if you get fluid leaving the back of the tube, in an amount equal to what the diaphragm can hold.

From there you could move onto the caliper... which I'd have an easier time believing needed a rebuild, if you ran into a situation where the fluid boiled. The caliper is in closer contact with the heat, I'd think. Not the master cyl.

Just thinking out loud...

Been watching this discussion in the shadows as I have the same problem with a rear brake. I have bled many a hydraulic brake system in the past without incident but this time I have just about had it. I pondered all the possibilities but told myself before I go spendin money on mastercylinder kits and such I figured I'd let someone else have a go at it
Here's what I did. Took it to the dealer and let them do it. Best $44.00 I've spent this month. I was so P.O'ed with the whole thing I'd a paid twice that. I was so happy to have the thing fixed I forgot to ask them what the secret is. I'm goin ridin, I'll find out later how they did it
O.D.

i ran a test using air and i made sure the caliper was working right and it was...so i mean i would have to think it was the mast. cyl. i ordered a rebiuld kit which was 40$ ..it should be coming in soon so as soon as i rebiuld it ill let you guys know what went on.

thanks for all yuor help!

i got my master cylinder rebuild kit and i installed that and the dang thing didnt even work..so being mad with the whole thing i just took it down to the shop. hopefully they will figure out what is wrong with it

just to be sure i would clean the disk just to be sure last time i was lubing my chain i got some on the disk