Your bike’s rear sag is very important. It should be checked often as it will change as the shock spring sacks and oil wears out. Too much and you increase the rake of your forks causing your bike to push to the outside of the corners or “hunt” for a berm. Excessive bottoming may also occur if you have too much sag. If there is not enough sag, your bike may under-steer, headshake, or seem harsh in the back.

Once you have the correct race sag set on your bike, you can check for proper spring rate by measuring the amount of static or free sag. This is the amount of sag the bike has under its own weight. If more than 30-35mm's, your spring rate is too stiff. If less than 15-20mm's of free sag, this indicates that your rear spring rate is too soft. Ideally, I like 25-30mm's of free sag on most bikes except for KTM's which I run 30-45mm's.

Setting your race sag is easy, here is my procedure…

1. Place your bike on a stand so your rear wheel is off the ground and mark your fender straight up from your rear axle. Measure the distance from the axle to your mark. This is S1 (or your "0" point).
2. Now put the bike on the ground. With handlebars straight, push down on the rear a couple of times and let the bike settle under its own weight (no rider). Measure the distance again. This will be your "free sag". Keep that number handy as it is important and will relate to your “rider sag” letting you know if you have the right spring rate.
3. Take the bike off the stand and get on board in riding position with full gear on. Have your bike close to a wall so you can lean on it for balance. Have someone push down on the back of the bike slowly and let it return up slowly (DON’T BOUNCE). Measure this distance. This is S2.
4. Now have someone lift the rear of the bike an inch or so and let it down very slowly until it stops. Measure this distance. This is S3. S2 and S3 will be a little different because of friction in your linkage.
5. Your race Sag is calculated by averaging S2 and S3 and subtracting this average from S1.
   Race Sag = S1 – (S2+S3)/2

For most bikes, I like 95-105mm of rider sag except for KTM's which I like 115-135mm's.

These procedures will also work for most 85cc bikes, except I like 15-25mm's free sag along with 75-85mm's rider sag.

Remember, it doesn't hurt to try different sag levels to find what works best for you. You can always go back.

Just like the oil in your cars engine, the fluid in your suspension must also be changed regularly.

Burnt up and contaminated suspension fluid can cause the following:

• Excess internal wear to your shock and fork cylinders from poor lubrication.
• Increased stiction (resistance to initial movement) as your fluid loses it's lubrication / slippery properties.
• Inconsistent and reduced damping at elevated temperatures because the viscosity properties have deteriorated.
• Reduced vehicle control.
• Oil change frequency in your car is determined by mileage; oil change frequency in your bike is determined by time.

Shock Oil Change Frequency Analysis:

To control your suspension movements, a piston plunges through oil creating resistance (damping) and generating heat. By the end of a moto your shock fluid can reach up to 300°F. This extreme temperature is achieved because the shock is relatively small and has very little surface area to dissipate the heat. Additionally the shock is shielded from cooling air by the air box.

A good rule of thumb is that for every 10° F rise in temperature, the life of suspension fluid is cut in half. Under 200° suspension fluid will last a long time. Once suspension fluid reaches about 200°, the polymer chains begin to burn up and the viscosity stabilizers break down. So to determine oil change intervals we must look at the time the oil spends above 200°. We will call this "Time At Elevated Temperature".

High performance suspension fluids last about 20 hours at elevated temperature before suffering significant viscosity breakdown and loss of lubrication properties.

To determine oil change frequency, the rider must determine when his shock has experienced "20 Hours at Elevated Temperature". A good rule of thumb is to subtract 5 minutes from every ride since it takes about 5 minutes to get the shock over 200°.

If an MX bike races a 20 minute moto, it counts as 15 minutes at temperature. Thus if you ride 4, 20 minute sessions, you put 1 hour on your shock fluid. So 20 days of riding use up your 20 hours of oil life. If you ride once a week, your oil is cooked in about 5 months. Obviously if you ride twice a week, you should change your oil in half that time.

Fork Oil Change Frequency Analysis:

Fork oil does not get very hot because forks do less work than the shock, there are two forks full of almost a quart of oil, and there is allot of surface area to dissipate the heat. Thus from a temperature standpoint, fork oil should last a long time. However, fork oil suffers extreme contamination from the sliding action inside the forks and the spring twisting and creating chips. These small metal particles become suspended in the oil and act as sandpaper in the oil.

Because of all the contamination, the fork oil should be changed often. To make your life simple, I recommend changing the fork oil whenever the rear shock is serviced. This ensures that both front and back are maintained on a regular basis and will minimize wear to your valuable components.

As oil, seals, and bushings get worn, forks will have a tendency to build up air pressure. This will make the forks start feeling harsh and wanting to deflect off small bumps. Your forks may have the need to bleed.

There is a bleeder valve located at the top of each fork tube off-center from the dampening/rebound adjustment screw. To bleed, start backing the screw out with a flat blade screwdriver until the screw is almost entirely out. You should hear any internal fork pressure escape as you back the screw out. Now, carefully turn the screw back in until it is firmly seated. Avoid over-tightening to protect the threads and the head of the screw.

I always bleed forks with the bike sitting on the ground under its own weight. Doing this will lengthen the time it takes for air to build up as well as improve the way the bike settles in corners.

Bleeding the air from your forks is easy and should be done every few rides. If you are getting a lot of air buildup, be sure to step up the frequency and consider a fork rebuild.

With the increasing popularity of 4-strokes, we are seeing a lot more engine rebuild work from our customers. And as we all know, when the time comes for repair, it usually isn't cheap as you have a lot more moving parts inside a top end than on a 2-stroke.

Most manufactures recommend checking the valve clearance every 20 to 25 hours and this time can add up quick! So to ensure that you stay on top of maintenance, the best thing a 4-stroke owner can do is add an hour meter on your bike.

Hour meters are simple to mount and every time the engine is running, so is the meter. Its fairly inexpensive and could save you big in the long run.

Hour meters are also an excellent way to keep track of hours on your suspension which should be serviced AT LEAST every 40 to 50 hours.

Whenever you get a new bike or install new rims on your bike, you must keep an eye on the spokes as they will have a tendency to loosen up.

As long as your rim isn't already "out of true", here is a tip on how to tighten the spokes and still keep the rim straight.

Start with the spoke next to the valve stem. Give it about a half turn. Now count forward to the 4th spoke from where you started and give it the same 1/2 turn. Keep counting every 4th spoke giving the same 1/2 turn until you eventually end up back at the one you started with next to the valve stem.

Now from that 1st spoke (where you started) go to the next spoke and give it a 1/2 turn. Then count every 4th spoke again and repeat like above until you end up back where you started.

Once you’ve tightened every 4th one again go to the 3rd spoke from the valve stem and repeat. Then follow the same procedure starting with the 4th spoke from the valve stem and repeat.

If the spokes are still a little loose then just start over and repeat the sequence again.

What you are doing is tightening all the inner left spokes first, then all the inner right, then all the outer left, and finishing with all the outer right.

Following this procedure, you will be able to tighten the spokes while retaining the trueness of the rim.

1. Install both forks and set fork height using calipers or a ruler. It is important that fork height be exactly the same for both sides. Tighten pinch bolts to the proper specs (Top: 18 Ft-Lbs | Lower: 15 Ft-Lbs).
2. Before installing axle make sure the end of it (and the edge of axle hole) has not been "mushroomed" from hitting it with a metal hammer. If theres any lip it must be ground off or fork will bind.
3. Install the axle (use rubber or plastic hammer only) and tighten the axle nut to proper spec (75 Ft-Lbs). If the axle turns while tightening, tighten one right side axle pinch bolt to hold axle in place.
4. Tighten both left side axle pinch bolts to spec (17 Ft-Lbs).
5. With the left side axle pinch bolts and axle nut tightened, loosen the right side axle pinch bolts. Take a small flat head screwdriver and carefully tap it into the slot between the two right side axle pinch bolts. This will enlarge the axle hole. You will then be able to grab the bottom of the right side fork tube and push it in and pull it out freely. You will be able to see the fork settle naturally into position on the axle without binding.
6. Remove the screwdriver and tighten the right side axle pinch bolts to spec (17 Ft-Lbs).

If you're wondering if your forks are currently bound up, put your bike on a stand and start this procedure at Step 4.