One of the first things that people usually talk about is
how to setup their suspension, and I have to say that for you to be truly happy
with your dirt bike you should do this set by step. Today’s dirt bikes are
amazing in the fact that they have an infinite ability to customize your bike to
fit you. Riders from every weight and height can be accommodated, but making
sure that you are getting all you can out of a bike is very important.

Motorcycle geometry is very important on today’s
motorcycles. If you look at a bike and think of all the time the engineers spend
adjusting the fork angles a half a degree at a time and how drastically it
alters the riding characteristics of the bike. You can imagine what a sagging
rear suspension can do to the fork angle, and how it may affect the handling of
your motorcycle. Increasing the fork angle would drastically reduce your
motorcycles ability to "hook up" in a corner. The front end would feel as if it
wanted to wash out during a turn, and it would loose the nimble feeling that it
should have.

First things first, initial setup.

If you purchased a new bike you should’ve gotten a manual
that tells you how to do this. DO NOT, and I repeat, DO NOT trust that the
dealership set your bike up at all for you. In most cases they simply pull the
crated bike out, slap on the front wheel, bolt down the bars and say "Here ya
go! That will be a $300 setup fee". If you purchased a used bike you may not
have gotten a manual to tell you what to do. Either way, read on.

So the first thing you should do before you even start up
your new bike is to check the fluids. I have heard stories about bikes that were
purchased right brand new from a dealer, and they were low on oil or completely
out. This also goes for antifreeze.

Check the tire pressures, typically a front tire runs
between 12 and 18 psi, and a rear between 10 and 14 psi. You may need to buy a
low psi tire gauge since regular car tire gauges aren’t very accurate at low
pressures.

Check the chain tension. Typically (and I emphasize
typically, not every bike) 3 fingers width of chain slack is acceptable. Some
bikes require more, some less. I have seen and heard of many bikes that come off
of a showroom floor with no chain slack, because it "looks" better. While you
are there, check the marks on the rear axle and make sure that it is equal on
both sides.

After you have checked your basics, now is the first
thing you need to do is set up the suspension. These specifications are in the
manual or online. I often use Race Tech to get the basic settings.

Put on all of your riding gear, with the bikes rear axle
suspended (not touching the ground) measure the distance from the rear axle to
the rear fender, straight up as possible. Write that measurement down. Now with
some help sit on the bike with all of your weight on it. You may need to be near
a wall or have someone help you from tipping over. Now here is an important tip!
Do not sit on the back of the seat! You need to sit in the center of your normal
riding position. Bounce up and down lightly to settle the bike and measure the
distance from the rear axle to the fender again. It is helpful to have the same
person measure the bike every time.

This is called "Race Sag". The distance the bike drops
with you on it needs to be setup and is critical to the bike’s handling
abilities. Typically the bike should sag about 3 to 4 inches with you on it from
being off of the ground.

Now if it’s not sagging enough you need to adjust the nut
on the rear shock to take the spring pressure off, and of course if it sags too
much you need to tighten the spring. This is called adjusting the "Pre-Load" .
There’s usually 2 nuts, one is a lock nut and the other is the spring nut. Back
off the lock nut.

How? Usually a long flat screwdriver and a hammer will do
the trick. Just tap it a few times to get it loose. Once it’s loose it should
spin freely. Do the same to the spring nut. But this one doesn’t spin freely
because of the spring tension.

Repeat measuring the distance until you get your bike’s
race sag within specifications.

Now here is the kicker. Most bikes are set up for
160-pound riders so the chances are you may need a heavier spring. Here is how
you check the "Static Sag".

Once you have set up the "Race Sag", take the bike, (no
one sitting on it) lift up on the rear of the bike and let go. The bike should
(check your specs) have about 1.5 inches of static sag. If you don’t have enough
sag you NEED a heavier duty spring. This will actually soften your ride.

Here is why, as you compress a spring , the spring by
design gets stiffer. As a spring is compressed the coils get closer and closer
together. Two things happen from this situation-

1. If the spring compressed too much, it is in the stiff
   area of itself and beyond its usable travel. The result is that the bike’s
   rear end is going to be harsh. This will result in a springy-tail happy
   feeling while riding. You can adjust your shock rebound but all you’re really
   doing is trying to mask the real problem. Like putting a sheet over a broken
   window and saying, "there, no one can see in now". Having a spring that is too
   soft will in effect reduce the rebound dampening of the shock, the rear end
   will want to slide out on a corner and the front end will have a tendency to
   cut or turn to sharp.
   
2. If the spring is already compressed and the coils are
   close together you will get what is called stacking. That is exactly what it
   sounds like. Under full compression the spring coils begin to stack up on top
   of one another, thus producing a solid piece of metal where your suspension
   used to be. I’m sure this doesn’t need any explanation what this does to your
   $6000 machine.

The ride you will gain from a heavier duty spring will be
softer because you are putting less "pre-load" on the spring. The initial travel
will be easier because the spring is closer to its relaxed position with less
"pre-load" on it. Some off-road riders can take advantage of this when
converting a motocross style bike for off-road use. If you go one or two heavier
on the shock spring than what is called for the pre-load is less each time. This
will result is a much softer feel for the first part of the travel. When you
live in Colorado as I do and are navigating through 4-inch to 12-inch rocks it
can sure help the feel of your body and butt at the end of a day. However! Going
too far can make the bike seem to wallow through the turns as the rear of the
bike will sag easily under acceleration. Also the rebound will have more power
over a heavier spring and may make the bike tend to squat more when hitting a
succession of large bumps. You probably will have to turn down your rebound
dampening. It does indeed depend on what you are looking for because for most
trail riders sacrificing a bit of cornering ability is well worth the more
compliant, softer, and forgiving suspension. Be careful that the spring is long
enough though, you don’t want your spring to be loose after installation. If
your spring is loose you needed a longer spring.

• You’ll need to remove the rear sub frame, not really
  difficult just time-consuming. Remove the plastic, take out the two lower sub
  frame bolts one on each side. Remove the upper bolt at the rear of the fuel
  tank, loosen the carburetor to airbox hose clamp and maybe your exhaust to
  muffler clamp if you have one - most bikes do not. Put the bike on a tall
  stand with the rear wheel clearly off of the ground. Remove the top and bottom
  bolts holding the shock on the bike and remove the shock. If the sub frame is
  off, the shock is usually fully exposed. Next back the spring nuts all the way
  until the spring is loose. On the bottom of the shock there’s a clip that has
  a slot in it, and another ring. Remove the slotted keeper and the spring
  literally falls off of the bottom of the shock. Watch the direction of the
  keeper and the shock ring. Install your new spring and reverse the procedure.
  Once you have the new spring on set the "Race Sag".
  
• Here is a tip, since the rear shock takes a lot of
  abuse and it only holds a few ounces of oil in it. If your bike is used or has
  a year or more of riding on it. Take the shock down to a motorcycle shop and
  have them change the oil in it. Most bikes with a few years on the shock have
  nothing more than foam inside. I have a small shop called Pro-Motorsports
  rebuild mine. With the shock off of the bike a rebuild, new oil, and fresh
  charge of nitrogen gas costs me about $60. It is well worth it to have this
  done.

Now that you have set up the rear you need to check the
front. Here again the chances are the dealership or the guy you bought your bike
from did not set up the front correctly.

1. Fork Alignment. This will need to be done every time
   you have a new tire installed or you remove your front wheel for anything. The
   forks are two tubes that are attached to each side of the wheel. These two
   tubes must be perfectly parallel, if they are not you will experience pre
   mature fork seal damage and leaking.
   
2. Check the triple clamp bolts to make sure they are all
   snug. You should torque them. Over torquing these bolt can crush the fork tube
   (on inverted forks). It can severely mess up your day if you damage these.
   These are almost always torqued in inch-pounds not foot-pounds. Loosen the air
   bleeders on top of the forks to release any air pressure (this should be done
   after every ride!).
   
3. Now you need to check the front axle torque, I also
   assume that a dealer would have slapped the axle on and didn’t set it up
   right. First loosen all 4 pinch bolts that tighten the forks to the axle. Next
   using a torque wrench torque the axle nut to specifications (I can’t tell you
   a number here because it could be torqued anywhere from 50 to 120 foot
   pounds). If the axle spins and you can’t hold it you may need to make sure the
   axle is seated on the nut side and tighten the pinch bolts on that side ONLY.
   
   
   
4. Now with the pinch bolts loosened on the fork leg
   opposite of the axle nut, get on your bike and hold the front brake. You need
   to compress the forks at least a dozen times or until the axle stops moving.
   If you don’t do this, the fork tubes are usually closer together at the bottom
   than at the top after driving an axle through them. When the suspension
   compresses you end up binding the forks, this damages bushings and seals. Ever
   known of someone who has their fork seals blow out of their forks all the
   time? This may be why. So after you get done aligning the front forks, gently
   get off the bike and tighten the pinch bolts (don’t overtighten these or strip
   them out). That’s about it for that.
   
5. Now you need to sit on your bike and set it up for
   your riding style. The handlebars can to be moved, yet I have known many
   people who never have even checked to see if they are right for them. It’s
   really easy, the bar clamps have 2 bolts per clamp. Lightly loosen only bolt
   one per side and this should allow the bars to be moved up and down. Find what
   feels comfortable for you both standing and sitting, but mostly where you
   usually ride.
   
6. After you have set up your bars, adjust the clutch and
   brake levers. This is easy to do as a little turn of an 8mm bolt will allow
   you to find where they feel best for you and allow you to reach them without
   thinking. Now word to the wise, don’t over tighten the clamps back down, and
   leave them slightly loose. You want to have your levers tight enough that you
   can’t move them but you can hit the mount or the lever with your palm and it
   will turn on the bar. If you watch many motorcycle videos I am sure you have
   seen the rider banging the levers back into position after a spill. I have had
   many tumbles and still haven’t ever broken a lever because they will spin
   rather than break.

Next is how to setup your suspension compression and
rebound settings. This is actually a little more difficult because if it’s a new
motorcycle you may not be able to tell. Truth is, all of the new models of
motorcycles are outstanding in the way they handle. If you take out a new
motorcycle without getting used to it some you won’t be able to feel what it is
doing what when you turn a screw this way or that way.

Now my personal recommendation is get a feel for the bike
before you start to tinker with the compression and rebound settings. Before you
can start to notice a difference you have to be able to go into a corner braking
over the braking bumps, or feel how the front end pushes or cuts when you are
making a sharp turn.

Now for the basic suspension design, which is actually
quite complex. You have a rear shock that is filled with only a few ounces of
oil and pressurized with nitrogen gas. The rear shock has two to three
adjustments, depending on your bike, which allows the rider to adjust the ride
characteristics.

The first setting is "rebound". This is designed to
control how fast the shock comes up after being compressed. The rebound is very
important to make your bike settle down after hitting a jump or any type of
bump.

If there is no rebound control the rear end of the bike
will pop back up immediately causing the tail to want to fly up and over the
front end. The front forks have rebound as well, and would do just theoppostite
in a jump, if you launched off of a jump the front forks would spring back up as
you left the jump causing the bike to wheelie in the air. In a turn if there is
no rebound on the front or rear the bike will never settle into a corner and
stick, it will however tend to feel tall and tippy. When going over a series of
whoops the bike will become uncontrollable and eventually flip itself and the
rider sideways (crossing up), I am sure you have seen live or on video a
motorcycle bouncing wildly through a minor section until the rider ends up going
over the bars. This is what no rebound will do to your ride. If you launch off a
jump the rear end will spring up, hitting you in the butt and throwing you over
your handlebars. Many broken wrists have happened from landings such as
these.

If you have too much rebound dampening, the rear end of
the bike will squat when you hit rough sections using up all of your suspension
travel by not allowing the suspension to return to full extension. This is
commonly referred to as "packing". The same is true for the front forks, too
much rebound dampening will reduce your travel with every hit and will sick the
front end of the bike causing it to get headshake at speed and cut too hard in a
turn. You hit a bump and the suspension goes down eight inches and returns only
six inches before you hit the next bump. That pushes the suspension down another
eight inches and the suspension only returns six inches. After a few bumps the
suspension is going to be sucked down with only a few inches of travel left, and
in the hardest part of the spring. Another thing having too much rebound
dampening on the rear shock will cause is the bike will not jump flat. When you
hit the face of a jump the front and rear suspension is supposed to compress and
upon hitting the apex of the ramp it will uncompress. If you have too much
rebound dampening on the rear shock the front end will uncompress and the rear
will not, this will send you through the air riding a wheelie. Sometimes almost
straight up and down, needless to say if you try to push the bike forward you’re
going to hit hard and go over the handlebars when the front end slaps down.

The ideal setup is a perfect balance of rebound for the
spring pre-load and the rider weight. A bike should jump smooth and flat, able
to cruise over a section of whoops with the rear wheel returning to full
extension just before the next whoop. In cornering the rear end should be able
to squat and stay squatted throughout the turn. A bike should be able to run
over a series of bumps and retain a smooth controlled feeling without packing
the shock or forks. Always allowing the suspension to ride in the race sag area
without getting tail happy. Sounds like magic? Well there is a reason that many
factory riders have a rear shock that alone costs anywhere from $12,000 to

$20,000.

Next thing the suspension does is control "compression",
the speed the shock and forks can compress under different riding conditions.
When you hit a bump or land the suspension has to be able to absorb the hit
without bottoming out, yet it has to allow full travel of your suspension to
absorb the hit, this is called "low speed compression". When you take a corner
the suspension needs to be able to compress to stick in the corner, but not so
far as to use up all of your travel. When you’re off-road the shock has to be
able to allow "high speed" hits such as rocks, roots, washboards, sharp edges
etc… to be immediately absorbed by the suspension. While these types of bumps
have less energy than that of a large jump, they hit the bike’s suspension
faster. If you have suspension that can only handle large jumps and big whoops
chances are the bike itself will be very harsh off-road when going over rocks
and roots. Today’s modern suspension is actually designed to do both with
complex valving and internal springs. They have made the adjustments on shock
absorbers able to do both high and low speed compression control.

However there is a limit to what a particular designed
shock absorber can do. This is why you see some dirt bikes as off-road only, and
others are sold for motocross use. When you have motocross only suspension that
can handle a 90-foot jump without crashing down, its design just won’t be able
to make off-road riding smooth (such as a YZ450F). The same is true for the
off-road motorcycles such as the KTM EXC / WR series of motorcycles. These bikes
have suspension that will gobble up any rock, root, gully, or chop you can throw
at it; but take them to a motocross track and they will begin to show their
weakness absorbing large hits without bottoming out. I guess what I am trying to
say is that if you have a motocross bike that you ride off-road mostly, you may
want to look into having the suspension re-valved and re-sprung to fit your
riding. If you are planning on converting an off-road motorcycle to a motocross
bike, good luck. The off-road bikes don’t have the geometry to be competitive
against today’s motocross bikes on a motocross track. But many riders are very
happy with full motocross bikes off-road after having some suspension work
professionally done.