Yamaha FZ-09 Forum banner
1 - 15 of 15 Posts

·
Registered
Joined
·
95 Posts
Discussion Starter · #1 ·
Just picked up a 2014 FZ09 with around 1000 miles on it. Took it for the first ride around the block and after a mile or 2 the front brake got stuck. It felt like the front tire went flat and the bike suddenly came to a halt for no reason. The brake lever feels like it's already compressed a little when I apply the brake more, and the bike is hard to push. What might be the problem?
 

·
Registered
Joined
·
877 Posts
Could also be some air in the hose that expanded or the return hole is plugged in the master cylinder.

Crack a fitting quickly and just enough to see fluid seep , with a rag around it, tighten and see if pressure relieved by rolling bike.

Squeeze lever and see if it still rolls freely after release of lever.

This would give a better idea of whether it's the master cylinder or air in the fluid.

I had a master cylinder that would lose pressure, at random.

Turned out to be a tiny flake of aluminum on the plunger seal, from the factory.
 

·
Registered
Joined
·
149 Posts
it COULD be a bad hose.
If there is a leak in between the laminated hose the fluid creates a bubble that locks the brakes, Happens a lot in the auto industry but you may have a pinched or defective hose.
 
  • Like
Reactions: Fizzerpilot

·
Registered
Joined
·
48 Posts
It could be the levers sticking, and also could be a bad hose. (Acting like a check valve) I would also check the fluid type to be appropriate (DOT 4) as having the wrong type brake fluid could cause this, and complete brake failure...
 

·
Registered
Joined
·
2,155 Posts
If it's a USED fz09...you can bet the previous owner put too much brake fluid in the reservoir..or he rebuilt the master cylinder incorrectly.

And thank you on your first post for spelling BRAKE correctly. Some of these guys think their break is broke.....or they broke the breaks. Drives me nuts when grownups can't spell.
 
  • Like
Reactions: 520FZ09

·
Registered
Joined
·
2,330 Posts
Excess water in the brake fluid will also cause this problem.

I recommend flushing the brake system.
 

·
Registered
Joined
·
539 Posts
Check to see if the hole in the lever is aligned with the plunger. And/or check to see if the part of the lever that actuates the brake switch is bent. If the lever doesn't full decompress it will build up pressure the more the lever is used ultimately leading to the brakes locking up. Happened to my Sv last year when I put new levers on.
 

·
Registered
Joined
·
50 Posts
Bike been dropped? If so I would bet Magilke441 has your answer. Happened to me after a bike fell over and tweaked the front brake lever.
 

·
Super Moderator
Joined
·
4,412 Posts
The most likely culprit is an overfilled brake reservoir. If there is not the slightest air gap showing in the brake reservoir sight glass when the bike is upright and level, you will need to remove a small amount of brake fluid. The simplest and quickest way is to take a small amount directly out of the reservoir.
Remove the front brake res. cover. Use the best fitting phillips head screwdriver you have and if the screws are difficult to turn,
tap lightly on the handle of the screwdriver with something lighter than a framing hammer. This can help to break free the screws.
Set the cover top side down, on a clean paper towel being careful not to lose the screws, nor get any hint of brake fluid on anything.
The fluid is caustic and will ruin painted surfaces. Now...remove a very small amount of fluid using a small piece of tubing, drink straw, or even a clean, folded paper towel (as a wick). You want to remove enough fluid to have an air gap in the reservoir to provide a space for the fluid that returns to the reservoir when the pads retract. Replace the reservoir cover, careful not to introduce any stray bits of lint, or whatever and snug up the screws a little bit on one side and then the other. Alternating and repeat until the cover is snugged up evenly.
Now, see if you can retract the brake pads away from the rotors. You can try using your fingers, but more likely you need to use something
non-gouging, like a flat head screwdriver covered with a shop rag. The idea is to wedge the pads away from the rotors without damaging/scratching
the pads or rotors. You can lever the pads away from the rotors by using the flat edge of the driver on the backing plate of the pad. Do not force the screwdriver
blade between the pad and rotor. If the pads don't retract, try removing a bit more fluid. Once you get the pads retracted, examine the rotors for discoloring caused by excessive heat and any warping. If all appears straight, with no obvious rotor discoloring or scoring, try gently pushing the bike a few feet on a level surface and ease on the brakes and see if they will smoothly contact the rotors and once the lever is released, the pads drag harmlessly on the rotors. If they pass that test, you can carefully proceed with a very short/low speed road test of a few yards. Steady and gentle at this stage. It's best that you have an empty residential street for this road test and don't stray too far from home base. Once the mini road test is completed, it is best to completely flush and replace the brake fluid with fluid from a new, unopened bottle of ordinary Pep Boys, Autozone, or Advance Auto DOT 4 fluid. Brake fluid replacement procedure should be easy enough to find on YouTube.

As always, keep everything clean and organized and go slowly when disassembling and reassembling the brake reservoir, etc., and take great care when conducting the mini road test. I am not a certified mechanic and I didn't even play one on TV, so the onus is on you when undertaking the system check, repair and road test.
If the rotors aren't damaged/warped...you got away lucky. I've seen folks that completely cooked their rotors from an overfilled reservoir. But those folks put on a bunch of non-stop miles for that to have happened. Let us know how it goes.
 

·
Super Moderator
Joined
·
4,412 Posts
So...did you ever get that front brake sorted?
It would be nice if you kept us updated on your progress.
 

·
Registered
Joined
·
962 Posts
The diaphragm in the master cylinder could be sucked down, causing it to not release the brake line pressure. Some people have to touch it when they open the master cylinder to top off the fluid... Remove the top, and check that the rubber diaphragm is folded up evenly and not sticking out...
 
1 - 15 of 15 Posts
Top