Front Master Cylinder

[blsnelling]

Is there any difference in the front master cylinders on a 300EX/400EX and a 450R? I noticed the brake lever feels much firmer on the 450R but that might be due to the calipers. I've rebuilt the calipers, rebuilt the master cylinder, and installed braided stainless lines on my 300EX and the lever can still be pulled back to the bars. They were vacuum bled so air shouldn't be a problem.

hm thats kind of odd having steel braided but being able to pull the brake lever all the way in. Maybe your brake pads are worn down quite a bit. I noticed today on my 400ex that my brake lever goes all the way in pretty easy so i'm thinking i need to replace the front brakes

[blsnelling]

Brand new brake pads too.

hmm thats really odd, I couldnt tell ya whats wrong. You said you bled the brake lines so i'm not sure hopeflly someone here can help though

[svahle]

I have a couple of thoughts.

1. I know you vacuum bled the brakes. But these brake systems are notorious for being difficult to bleed. I just seems that air gets hung up somewhere despite proper bleeding. You might try it again. You might search to get information on more methods of bleeding. Some use a syringe to push fluid in from the bleeder. Air wants to go up to pushing fluid from the bottom helps the air go where it wants to anyway.

2. I see that you rebuilt the master cylinder but it might still be the culprit. Even when rebuilt, some just don't build the pressure they do when they are new. What I have done is replace the stock front lever, reservoir and master cylinder with one off of a YFZ. This is nice because the brake lever on the YFZ is adjustable in and out so you can get the lever in the position that feels most comfortable. I've picked them up off ebay for between $10-$30.

3. I know you rebuilt the calipers but did you thoroughly clean all the parts? The calipers can get gummed up and don't slide as well. Also, the pistons can get sticky. These things together can lead to a soft brake lever. Make sure the slides and piston are clean and grease the slides that allow the caliper to "float". Also make sure the slide pins for the pads are smooth and greased up. I use fine sandpaper to smooth out all the slides and then grease them up real good.

I'll bet one of the above will fix the problem.

[blsnelling]

These brakes have been bled and bled and bled. Nothing doing.

The calipers are clean with new seals and are not sticking.

The slides are clean and lubed.

I'm ready to try a different master cylinder. That's why I posted what I did. I'm going to take you up on your suggestion and try to get one off a YFZ. Might as well. I've already got FYZ front shocks on it:)

Thanks for the tip.

[EX LONERIDER]

just curious, but did you try bleeding the lines individually? cracking the fittings loose one by one working your way up? just an idea... had a similar problem in my sand rail. bled it at every fitting point till it bled all the air out and worked.

[blsnelling]

Yes, I did all that with the stock brake lines. It was after that that I bought the stainless lines. I've got a YFZ master cylinder on its way now.

[Aceman]

You could try Speedbleeders, I think they're about $7-8 bucks apiece. They're not exactly cheap, but you know your brakes will be bled completely.

[blsnelling]

I got the YFZ450 master cylinder and finally have good "pedal". I appreciate the tip on using one from a YFZ. I do like it better than the Honda part.

[svahle]

Originally posted by blsnelling
I got the YFZ450 master cylinder and finally have good "pedal". I appreciate the tip on using one from a YFZ. I do like it better than the Honda part.

Good to hear that you got it worked out.

I just bought another 250r and it has a front master cylinder off of some kind of crotch rocket. It also has an adjustable lever and feels very strong. Might keep that in mind for the future.

[07250ex]

Odd its tough to fully get my front brake lever all the way in on my 250ex but not impossible =/ 450r's are known to have really good front brakes