Circular motion: Brake rotors need TLC
to maximize their pucker power.
BRAKE MY HEART
The brakes on my CRF450 were
never very good, and they seemed to
be getting weaker with each passing
ride. Then I blew a fork seal and
slathered them with fork oil. What
are the steps I should take to get my
brakes up to snuff again?
Even if you hadn’t gotten oil on
your front brake rotor, it sounds like
your brake rotor was already
contaminated. Brake rotors need to
be cleaned at regular intervals. Why?
Because as your brake pads squeeze
down on the brake rotor, they leave
a little material behind. Eventually,
enough ground-up dirt and brake-pad
material will build up so that your
pads are no longer clamping down
on the actual rotor. This is why it’s
important to clean the rotors, even if
they stay relatively uncontaminated.
You shouldn’t have waited for your
fork seal to blow before cleaning
your brake rotors.
It is important to note that even an
oil-contaminated rotor can be cleaned.
As long as the rotor is straight and
it’s still over the minimum thickness
(MMTH printed on the rotor), it’s
good to go. Contaminated brake pads,
however, should be replaced.
Here is how to clean a rotor. First,
clean off the oil with contact
cleaner, then remove the wheel from
the motorcycle and remove the brake
rotor from the wheel. Once you have
the rotor off, the ultimate way to
clean a brake rotor is to use a sand
blaster. Besides improving performance, sand blasting a rotor once
or twice a year can actually double
its lifespan. For the average person,
however, 400- to 600-grade sandpaper
is much more accessible than a sand
blaster. Use the sandpaper to work
your way around each side of the
rotor’s brake-pad contact area. Use
small, circular sanding motions to
sand off the debris. Change the sand
paper as it gets contaminated.
Once the sanding is done, wash the
dirty rotor with soap and water. You
can use contact cleaner to eliminate
any oil residue, but because contact
cleaner contains chlorides that can
leave a film, wash the rotor with soap
and water afterward and vigorously
dry the rotor with a clean cloth towel,
making sure to collect all of the gunk
and residue that you knocked loose
with the sand paper, contact cleaner
and soapy water.
It is best to install brand-new brake
pads, but you could try to sand your
old brake pads. To do this, you need
to remove the brake pads from the
caliper, tape a piece of sandpaper
down on a flat surface, and swirl the
brake pad in a circular motion on top
of it. Sand until the surface of the
brake pad is clean and flat.
Before reinstalling the brake pads,
make sure that the pad’s backing
plate is flat. Excessive heat can warp
the backing plate. A distorted backing
plate can cause uneven wear, erratic
heating cycles and decreased lifespan.
Set the backing plate on a flat surface
to check it. If the pads are bent,
order new pads.
After you reassemble your brakes,
take the time to bleed the brake fluid.
Mystery: Check the black plug on the
bottom of the 2011 RM-Z black box.
MY SUZUKI RM-Z450 DOESN’T
My 2011 Suzuki RM-Z450 has
trouble starting. When it runs, it
seems okay, but sometimes it just
stops completely. I can’t trust it
enough to ride it. Help?
Once you have checked the
wiring junctures, changed the
spark plug and disconnected the
kill button, you have done all the
easy stuff. The next step is to
move to the black box. Pull the
black box plug out of the bottom
of the black box and look for dust,
debris or water in there. Spray it
with contact cleaner, hit it with a
little dielectric grease and plug it
back in. If that doesn’t fix it, borrow a black box from another 2011
RM-Z450—tell your friend that you
will only need it for a few minutes.
If this fixes your problem, then you
need a new black box. If it doesn’t
fix it, you have more serious issues
and need to seek competent help.