Dear Mr. Know-It-All,
I’m hoping that this is a reasonable
question. I have a new Kawasaki
KX450F with the air fork. I intend to
use the bike for off-road and desert
riding. I know that most fork-seal
problems are from the front tire
throwing rocks at the back of the
steel fork tube. Naturally, with the ter-
rain and speeds of desert racing, I am
worried that there might be damage
to the surface that would allow the
fork to lose oil and then air pressure.
Should I be worrying about this?
While this might seem slightly
paranoid, it is a reasonable question.
If the seal were to be damaged badly
enough, the fork could lose pressure.
It is extremely unlikely that the fork
legs would both suffer such severe
damage at the same time; however,
the life of a lower fork tube is not a
safe one when you are racing desert.
The small, gritty rocks and gravel
common in desert terrain do get
caught in the knobs and can be
thrown at the back of the fork legs in
high-speed sections. The subsequent pits and dings in the steel tube
surface can and will cut the seals.
Generally, the area affected is within
a few inches of the upper tube, so
Shock Soxx, Seal Savers and other
MR. KNOW IT ALL MR. KNOW IT ALL
Dear Mr. Know-It-All,
I love to look at the factory bikes
when I attend a national motocross or
Supercross race. What can I learn
from those bikes that will help me
with my bike?
Some of the really fine craftsman-
ship you see in the pits of a national
event has very little to offer the aver-
age rider. Even the clever safety
wiring on key fasteners would not be
needed if the team hadn’t replaced
the stock steel fasteners with titanium
or aluminum. I have included two
photos. One photo is of a works KTM
with grip tape on the frame. The tape
keeps the bike looking good, but it is
very hard on gear. You have to decide
whether wearing out pants and boots
is worth the added grip. Finally, there
is a shot of a works Honda footpeg.
What a work of art that is! A peg that
sharp would shorten the life of your
boots by as much as 80 percent.
That’s not a problem when you get
free boots, but it might not be something you want to deal with.
On a side note, one thing you see
in the pits that you really don’t want
to copy is the way the factory bikes
are cleaned. Do not use a pressure
washer to blast dirt and mud away
like the factory mechanics do. Even
though you see them do it at the
sorts of neoprene covers help a lot.
At the Havasu round of the WORCS
races, desert legend Larry Roeseler
was running Seal Savers and riveted
on a second fork guard to protect
the back of the fork—much like the
stock KTM fork guards. The KTM
fork guards will fit on a Honda, but
not on a Kawasaki. We have also
seen riders attach a plastic bottle at
the top of the fork guard. In any
case, protecting the back side of the
fork leg (not just in the desert) is a
good idea. Nicks in the black DLC
coating look terrible, and the fork leg
itself is very expensive.
Dear Mr. Know-It-All,
I have a 2006 YZ450F with a car-
bon fiber exhaust, jet kit and a Uni fil-
ter. Most of the time the header glows
orange while I am riding. I took it to a
shop, and they told me it was normal.
Other people I ride with think that it is
probably not jetted right. Who is right,
the shop or my friends? I just want to
fix what is wrong with it!
This isn’t a totally stupid question,
but part of the answer is that you
bought a stupid pipe. In a way, both
the shop and your friends are right—
and wrong. It is “normal” for the header
pipe to get white or red hot on a modern four-stroke. Generally, this isn’t visible unless you ride in the dark, and it is
most common when the engine is
unwisely allowed to idle for extended
periods. The shop is assuming that is
what you are talking about. I suspect
that the “carbon pipe” you bought is a
big-core, open, loud, stupid pipe that is
bad for the sport, your ears and, in this
case, your engine. You may have jetted
the bike richer, but probably not rich
enough for such an open exhaust. Go
two or three sizes richer on the pilot jet
and a bit richer on the main jet as well.
See if the engine likes the extra fuel,
and see if that changes the color of the
header. A quieter, more sensible pipe
would also help, but you weren’t smart
enough to buy one the first time
around, so I hold out little hope that
you will do it now.