2014 YZ450 Front Brake just horrible?

[APlusAutoParts]

i have been riding yamahas since 09 i have purchased a new one every year, my 14 now has 4.3 hours on it and the front brake is already fading (spongy) this has never happened before on any of my other yamahas, if i had to complain about this 2014 model that would be the only negative thing i can say about the bike its simply put the best bike i have ever rode in my life. any suggestions on the front brake brake problems. i have heard of people putting honda master cylender on the bikes and that they fit no problem, a few of my friends ride hondas have over 100 hours on them never thouched them and there brake isnt spongy at all

[grayracer513]

As to specific recommendations for the '14, I'm not at all sure which Honda master would interchange, and whether there is actually any difference between that and what's on there now.

 

One thing that absolutely will improve the stopping power is an oversize rotor.  But, if it was OK when new and now it isn't, it's probably pads causing the problem.  Try matching them up to a current set of Honda CRF450 pads. 

[WouldsAssassin]

My 2011 was getting the spongy feeling that everyone is complaining about with their YZs. Mine is no longer spongy. One thing I did was to pull the lever back and wrap the lever overnight under pressure. It helped but was only temporary fix. Now before every ride i just squat down and sqeeeze the caliper itself to push the pistons in and force any air in the caliper up the hose. A few squuezes of the lever to drive the pistons out and repressurize the lines and i have solid brakes all day. After following this practice for a few months I think I finally got all the little bubbles out of the line. My brakes are very solid and other than the rotor are all factory equipment.

Give it a try.

Edited March 28, 2014 by WouldsAssassin

[APlusAutoParts]

that sounds interesting assasain, but to add to my issure as i tool my bike off the stand and i had no brakes after pumping up the caliper it got some pressure back but i barley had any brakes of course i still rode but living in ny it was only for 45 minutes before the wonderfull ruined another weekend.

[APlusAutoParts]

to ad to my brake problems i raced this weekend i got cross rutted went down on the right side not that hard, i picked my bike up and my front brake lever felt as if i was holding it half way to the bars and when i check for dirt or something in the lever area it was clean so i just kept on going, shortly after that my front wheel locked up and i had no feel from the lever at all. i waited a little on the side of the track. after a little while the front wheel became free and i rode back to my truck. at this point the front brake felt as if there was no fluid just no reaction at all and it was still half way back. my friends were saying the lever is bent i took a brand new one and compared and it was not bent at all. i figured my day was over so i ate something, after that i went to move my bike and the brake was fine moved freely (still spongy) so i raced my last 2 motos with no problems. since my last post and before this weekend, i blead the system completely, no change. then i rebuilt my master cylender again no change. i would really appreciate any suggestion as early as possible im thinking at this point its either the brake line or the caliper i mean whats left out of the system and remember this bike is brand new. thanks

[grayracer513]

If the wheel tied up on its own, that normally means that the master cylinder piston is being prevented from returning to its normal at rest position.  When this happens, the fluid cannot back up into the M/C reservoir as it expands from heat, and the pressure gets applied to the pads.

[APlusAutoParts]

i agree gray but why is this happening on a bike with now 6 hours on it

[grayracer513]

I can't tell.  The bike is about 1000 miles outside the range of my psychic vision abilities.  You'll need to look it over and see.  It sounds related to the crash.

 

If the plunger length between the lever itself and the master cylinder piston is adjustable, be sure you don't have it too tight.

[Mutley53]

Make sure when you rebuilt the master cylinder you didn't put the shaft behind the lever in backwards. The ends are not the same size and if put in wrong the brake will not release, eventually locking up. I made that mistake.

[APlusAutoParts]

trust me i didnt i just dropped it off today at a shop over here, if you remember i was having problems at 4 hours before i touched it

[APlusAutoParts]

i just got the bike back last night in the end the master cylender was no good, he told me i rebuilt it properly he couldnt figure it out swapped out the master with one from a kawasaki and the brakes are great i guess ill have a little green in me from now on lol

[HRC]

I always put a 270 rotor on all my Yamahas ...stock is to weak for my taste

[WouldsAssassin]

i just got the bike back last night in the end the master cylender was no good, he told me i rebuilt it properly he couldnt figure it out swapped out the master with one from a kawasaki and the brakes are great i guess ill have a little green in me from now on lol

Glad it's fixed. Quality control is tight on all the parts of a motorcycle but sometimes one gets through that doesn't cut the mustard. Enjoy your ride.

I read a few years back that the average car has 20,000 parts in it. If 20 parts are off spec and give you problems that's still a 99% rate of infallibility. I shoot for perfection but that's better than I could ever do in my work.

[APlusAutoParts]

interesting way to put it assassin, i raced this weekend brakes were great, bike is amazing although i had a little trouble with the rider opertating the bike lol

[Otto646]

I had the exact same issue with my 2014 with about 4 hours on it! I tried putting an old over-sized front rotor on it from my 2012 yz450f and that didn't help at all. A buddy of mine suggested a braided brake line so I tried that and the brakes have been the kitties titties ever since

[CZRoger]

Will a SS front brake line for the 2010-13 fit the '14?

[WouldsAssassin]

Do I have the only YZ450F that came with a braided stainless steel front brake line? No the one in the dealership I looked at also had one...

 

Pull back the rubber sheathing on your brake line and check for me. I can't have one of two YZs to ever come factory equipped with a braided stainless brake line.