possibly fatal technical issue (brake fluid)

[grommit]

Originally Posted by HavBlue

What year is this manual and what page did you get this from. In the 2004 manual you will find the Warning on page 4-18 and you will note it says nothing about replacing fluid unless the system is disassembled meaning internal parts not simply changing pads.

It is mentioned in both the 2007 service and the owners manual. Here is another extract...

Changing the brake fluid
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the NOTE after the periodic maintenance
and lubrication chart. In addition,
have the oil seals of the master cylinders
and calipers as well as the brake
hoses replaced at the intervals listed
below or whenever they are damaged
or leaking.

Oil seals: Replace every two years.

Brake hoses: Replace every four years.

[DefyInertia]

Hav, it would probably be prudent to flush your system and look it over closely while it's apart and empty. You've got a 2004 with some miles on it and you "hit 100MPH EVERY time you ride" so I would say your OEM hoses are at high risk.

Will I be replacing my oil seals every two years, no...but I do look everything over to check for anything that needs to be replaced and flush the system every time I change the pads. It's cheaper than an oil change (and less frequent, especially for you) and take sabout the same amount of time...mityvac FTW!

[Fred]

Originally Posted by phxtravis

I believe the only advantage to 5 is the fact that it will not eat paint.

DOT5 isn't hygroscopic like 3 and 4. But that also means that if you get water into the brake system, you cannot easily flush it out like you can with DOT3/4.

DOT5 is also slightly compressible when it's hot. We're taught in physics class that liquids don't compress. DOT5, being silicone based, will compress. Silicone is weird stuff. So DOT5 can give you a spongy brake when it's hot. Many racers dislike it for that reason, as they get their brakes very hot.

Fred

[CanadianFZ6]

Originally Posted by grommit

It is mentioned in both the 2007 service and the owners manual. Here is another extract...

Changing the brake fluid
Have a Yamaha dealer change the
brake fluid at the intervals specified in
the NOTE after the periodic maintenance
and lubrication chart. In addition,
have the oil seals of the master cylinders
and calipers as well as the brake
hoses replaced at the intervals listed
below or whenever they are damaged
or leaking.

Oil seals: Replace every two years.

Brake hoses: Replace every four years.

I realize it says that in the manual... but it is very simple to change the brake fluid yourself... I have done it for all my bikes and takes less than an hour to do.

What you need..
8mm wrench (not socket)
clear plastic vinyl tubing (I think it is 3 eights...)
container for used fluid
Philips screwdriver
Dot 4 fluid from a sealed container

1) Put the bike on the centre stand and level the brake reservoir (move handle bars so the reservoir is level)
2) Take the rubber cover cap off the bleeder screw on one of the front brake calipers (looks like a grease nipple)
3) Put the clear vinyl tubing over the bleeder screw (making sure it's snug so it don't leak)
4) Open the brake reservoir on the handle bars
5) while holding pressure on the brake lever (this is important not to let go until you close the bleeder valve)
6) while holding pressure on the brake (DO NOT PUMP THE LEVER JUST USE CONSTANT PRESSURE) crack open the bleeder screw with the 8mm wrench... the lever will come to the bar (don't panic, that's what is supposed to happen) and fluid will start to flow out of the bleeder screw into the vinyl tubing. You obviously need two hands for this. DO NOT let the lever go (it should be against the bar by now... Now close the bleeder screw and Then let the lever go slowly.... the level in the reservoir will drop a little...
7) Repeat 6 over and over and over... pressure on the lever, open bleeder screw, squeeze the brake lever until it reaches the handle bars, close bleeder, realease brake...
8) As the fluid drops in the resovoir, start adding new dot 4 fluid until you run a few hundred ml through the lines... as everytime the level drops in the reservoir to about 20%, fill it back up. Never let the level drop below the hole in the bottom of the reservoir... add new fluid when the level gets down to about 20% or so...

Repeat for the other front caliper

Key, don't pump the brakes and squeeze gently so fluid doesn't squirt up out of the reservoir instead of going through the vinyl tubing... do not realease pressure on the brakes if the bleeder valve is open...

I have done it this way for nealy all my bikes and never got air in the system... takes about an hour to do all the brakes, including the rear (same way, except you are pushing down on the brake pedal instead of squeezing the lever)