Rugged North - Content

by Gary Semics

“Must-Do Bike Setup Adjustments”
Written By: Gary Semics

Intro: It doesn’t matter if your bike is stock or modified. Having all the components adjusted properly is very beneficial for consistent fast lap times and a comfortable and controlled feeling on the track. Following are some basic adjustments that should be made on any bike for your weight, skill level, and how you personally want the bike to handle and feel.

Adjusting The Controls…

One thing that is almost always over looked by beginners is the importance of adjusting the controls on the m/c. We're talking about the clutch, throttle, gear shift, and front and rear brakes. I've seen controls adjusted so poorly and so bent up, that it's impossible to use them correctly. These kinds of things are what hold the beginner back from improving.

His/Her controls are not operating correctly, so he/she doesn't learn how to use them correctly. Let alone learn to use them so well that they become an automatic reflex reaction. If you want to ride better, make sure your controls are set up and adjusted perfectly every time you ride the m/c.

Mastering the use of all five controls is definitely a fundamental you have to master in order to ride like a pro. You can’t just master them, however. You have to be able to use them like they are a part of your own hands and feet. You got to be able to mix that tranny, use that low-end lever, feather that front brake, feel the breath of that throttle, and lock or feather that rear brake. And you have to be able to do all this at the same time, automatically, and with perfect control of each one.

Hey, I never said it was going to be easy. In M-X, there's no easy way. There's just the right way. And besides, if it was easy, everyone could do it and it wouldn't be a challenge. When you study and know how this is done, with the right kind of practice, you will develop these skills.

One thing a pro does every time he throws a leg over that m/c is make sure all the controls are adjusted perfectly. The controls are a part of his reflexes, so he wants them adjusted where he's used to them. In the
following section, we're going to cover the adjustment of each control. We'll start with the gearshift adjustment.

Gearshift adjustment: Make sure the gearshift lever is always tight on the spines and adjusted to the right height in relation to the foot peg. It should be about level with the top of the foot peg. Down-shifting is easy, but getting your foot under the shifter for a good throw through the up-shifting movement, while your in the forward body position, takes a little more skill. If your gearshift lever is adjusted too high or too low, it will be difficult to shift from different body positions. Therefore, the rider will compensate the correct body positions in order to shift. To avoid getting stuck with this bad habit, get that shifter adjusted right.

Clutch and throttle adjustment: Another thing a pro does is service the clutch and throttle cables and the throttle housing regularly, in order to keep them working slick and easy. Most beginners don't service the clutch and throttle often enough and after a while, it becomes even more difficult to have good clutch and throttle control. This is because the clutch and throttle become too hard to pull and turn.

Keep the clutch perch adjusted to a slight downward angle and move the clutch perch in on the bar so the end of the clutch lever is in before the end of the grip. The middle of the clutch lever should touch the grip before the end of it. If your clutch lever is slightly bent and the end touches first, use a box end wrench to bend it back.

Adjust a slight amount of play in the clutch lever so the engine can fully engage, and yet you can fully disengage the engine with one or two fingers. With the correct adjustment and the correct bend of the clutch lever, this is easy. Without it, it's impossible! Many riders have never learned to use the important clutch techniques correctly, when all the while the clutch was never set up right.

Rear brake adjustment: The rear brake should be adjusted just a little higher than the foot peg (about an 1/8”th to a ¼” inch higher). This is so you can use the rear brake when you’re in the back and the forward positions. If it was adjusted too low, you couldn't reach it when your body position was back.

This is where your hardest braking will take place. It's not good to have the rear brake pedal adjusted too high either. This is because you'll brake too hard when you’re standing with your body position in the middle of the m/c. For good, controlled braking, through your range of motion, get that rear brake adjusted right and get used to it.

Front brake adjustment: The front brake perch should be adjusted at about the same angle as the clutch perch. This is so it's in a comfortable position to use and you can feather the front brake and the throttle at the same time. This is a very helpful technique in certain bermed corners. When you open the throttle you automatically let go of the front brake.

Most pros like enough free play in the front brake lever so their front brake finger is fairly closed when they’re using the front brake. This allows them to hold on better and have more throttle control. A lot of beginner riders don't use the front brake very much. Many of them don't use it at all! The front brake has the most stopping power.

If your one of those riders who has trouble using the front brake, it's just like any other technique. You have to work at it more. Set up a practice drill and frequently work at that front brake. You'll be surprised how fast it will become an automatic reaction when you race. And to make it possible to learn, make sure that front brake is adjusted right. The adjustments of these five controls are very important. If you want to gain speed and control, make sure your five controls are adjusted and working perfectly every time you ride.

The adjustment of the angle of the handlebars is also very important. A good reference is that the grips should be close to parallel with the ground.

Other Adjustments…

The jetting of the carburetor: The air/fuel mixture is a critical element for throttle response and horsepower...

Suspension: Springs for your weight and spring pre-load.

Suspension: Clicker adjustments for front and rear suspension (rebound and compression).

Chassis: Setting the height of the fork tubes in the triple clamps.

Tire selection and tire pressure.

60 and 80s: Most of these same set-ups will also apply to the 60 and 80cc bikes. The only differences are in the tire pressure and rear shock preload. For 60s and 80s the tire pressure should be 12 LBS for both the front and rear. The free sag and rider sag for the rear shock spring should be between 10 to 25mm (free sag) and 75 to 85mm (rider sag).

Four Strokes: These same adjustments will also work for four strokes accept for the jetting of the carburetor. The carburetors are similar, but a little different. And of course, the sound is a lot different.

The Motor: The main thing that you’ll have to adjust, in relation to the motor, is the jetting of the carburetor. You may get lucky with some bikes and the jetting may just happen to be right on. However, this is not usually the case. The reason for this is that the manufacturer can’t produce the correct jetting for every location where the bikes will be sold. This is because there are three main climate conditions that greatly effect jetting. They are temperature, humidity, and altitude.

There are three main parts of the carburetor that effect the jetting and they translate to three ranges of throttle positions.

First of all, there’s the idle adjustment, airscrew, slide, and pilot jet. They work together and affect the first quarter of throttle movement (from off to a quarter throttle). Then there’s the needle and clip position. This covers the mid range of the throttle (from quarter to three quarters throttle position).

Finally, there’s the main jet. This affects the performance of the motor from three quarters to full throttle. You’ve heard the familiar saying, “on the main jet”, well, that’s pretty much wide open! It doesn’t matter what RPM the motor is running at, when the throttle is in a certain position the motor is controlled by the corresponding part of the carburetor. What you have to make sure of is that all parts of the carburetor are adjusted right for your environment, temperature, humidity, and altitude.

How important is this? Well, if Ezra Lusk’s mechanic moved the needle clip position one step off of where it should be, his bike would instantly become slower than a stocker in the mid range power area of the motor. So having the jetting spot on is very important for top performance out of the motor. Sometimes, the factory mechanics slightly adjust the jetting between motos when the weather changes. You don’t have to be that
particular, but being in the ballpark would be a big help.

Another important factor with jetting is that different parts of the jetting do overlap with each other and slightly affect the entire range of the jetting. An example is changing the pilot jet will have a slight effect on the main jet. For the most part it is as I just described earlier.

Suspension: The adjustment of the suspension for the forks and shock has to be stiff enough not to bottom out on the big hits and soft enough to move and soak up the chop. It also has to work in the correct parts of the travel -- the beginning, middle, and end of the travel. It should pick up the chop (small bumps) only in the beginning of the travel and absorb the big hits by using all of the travel. Spring force and dampening or valveing controls the suspension.

Damping or valving deals with oil flow hydraulics. In reference to the dampening, there is compression and rebound dampening. The compression dampening controls the movement of the travel from fully extended to fully compressed. The rebound dampening controls the movement of the travel from fully compressed to fully extended.

The only thing pushing the travel back, on the rebound side of things, is the spring.

Since this is the only force that the rebound has to deal with, the rebound is less complicated than the compression. This means the compression dampening is more complicated, and therefore, more important. Next, there are two main parts of the compression and rebound dampening, the low and high speed.

The low speed is where the suspension is just using the first half of the travel or so, going back and forth, traveling through the first half of the range of movement. The high speed dampening is when the suspension quickly moves through it’s full range of movement, like when you land from a big jump, compress into a hard g-out, or hit a big whoop or bump.

What works hand in hand with the dampening are the springs. The dampening controls the movement of the travel and the springs control the position of the suspension, like what parts of the travel the dampening is working in. It’s impossible for the manufacturer to set up the bikes with the correct springs and dampening for everyone. That’s because of different size riders, skill levels, and conditions.

They try to set the bikes up as close as possible for a 160 to 180 pound intermediate rider. This is about the average, middle of the road setting. Faster riders hit bumps and obstacles harder, so they need stiffer suspension. And of course, the heavier you are the stiffer it needs to be. Like many things, there is a compromise. You have to find the correct balance, not too stiff, not too soft. This is so it works well on the small bumps and doesn’t bottom on the big hits.

The pre-load is the amount of tension on the spring when the suspension is at full extension. This deals with free sag and rider sag. Free sag is the amount the bike settles from full extension to being under just it’s own weight.

Rider sag is the amount the bike settles from full extension to being under it’s own weight and the riders weight when he’s sitting in the center of the bike, on the front part of the seat. These pre-load adjustments are very important, especially for the rear shock. A good rider can feel the difference of just 3 millimeters. These pre-load settings also affect the handling characteristics of the chassis.

The chassis: The motor powers the bike, the suspension controls the movement of the wheels through their range of travel, and it’s the geometry (the chassis of the motorcycle) that controls the way it handles, steers, and feels. There are many aspects to the geometry of the motorcycle, but for obvious reasons, we’re just going to cover what adjustments you can make.

The height of the front and rear of the motorcycle have to be somewhat in balance. You accomplish this with the pre-load, suspension settings, and the height of the forks in the triple clamps. When the front of the bike is lower it will steer quicker.

This is usually better for tighter, hard-packed tracks. When the front of the bike is adjusted higher, it won’t steer as quick, but it is more stable at higher speeds. So, this is better for faster tracks and soft terrain tracks (mud and/or sand).

Again, there is a compromise. These settings would be much simpler if it wasn’t for the movement of the suspension. You see, as the suspension changes positions in it’s range to travel, it also changes the overall geometry of the motorcycle. This is one more reason the suspension has to be balanced in regards to pre-load, spring rate, and dampening. Having this balance and setting the forks at the correct height will give the bike that ever-important neutral starting point to work from.

Tire Selection and Tire Pressure: Rubber compounds and tread patterns have become a real science in the motocross industry. Having the right rubber on for the different track conditions is a big advantage. One important decision all the pros have to make at every race is tire selection.

The correct tire can mean as much as two seconds a lap. The right tire will also get you out of the gate better and improve your starts. The front tire is just as important as the rear because having the front-end slide out in corners is just as bad as loosing traction and spinning too much in the rear.

The common rule is that for softer terrain, like mud, sand, or grassy loam, the deeper and more spaced the tread pattern should be. This is so the tire can get a good grip into the soft dirt and keep itself from clogging up, keeping itself cleaned out. The harder the terrain is, like clay and blue groove tracks, the shorter and more close together the tread pattern should be.

This is so the tire can get more rubber contact with the ground and hold onto the hard surface better. The good racing tire manufactures (like Dunlop Tires) will have the correct rubber compound built into the different type tires. A different style of sidewall is also built into the different types of tires.

This means that a soft terrain tire for mud and sand will be made of a harder, stiffer rubber compound than a hard terrain tire. It would be to your advantage to understand the different types of tires available, so you can have the right tires on for the tracks you’ll be racing. Check your local dealer for a Dunlop Tire chart.

Let’s face it: tires aren’t cheap, so to get the most life out of your tires you can keep the worn ones for practice. You can even turn the rear tire around for even longer ware, putting the sharper edge to the front. But, when the track is a little on the wet side and the ground is rather hard, it’s very important to have a good sharp edge on the tires.

It takes a sharp edge to cut into this kind of surface. I’ve seen lap times improve as much as 45 seconds a lap when a slippery wet track began to dry out and the main lines started to get tacky. Having the right tire on can’t quite make that much difference, but it does make enough of a difference to be a major issue on race day.

Tire pressure not only effects traction, but also how the tire feels on the track. The softer the terrain, the softer you can run the pressure, but if you go too soft you’re taking a chance of having a flat. With too little tire pressure, the sidewall can flex so much that it will pinch the tube. Too little pressure can also let the tire turn on the rim, causing the valve stem to rip out. Also, watch out for rocks. Rocks can smash the sidewall against the rim and pinch the tube.

On harder surfaced tracks, you’ll have to run a little more tire pressure. Not only will this guard against having a flat, because you’re more likely to get a flat on a hard surface track, but it will also take more tire pressure to keep the side wall from rolling out in corners. Keep in mind, as I mentioned earlier, these factors are built into the different types of tires. So the hard terrain and soft terrain tires are already going to be made for the hard and soft tracks.

The tire pressure range isn’t very broad. In the front the range is from 11 to 13 pounds. And in the rear it’s from 12 to 14 pounds. I know that doesn’t sound like very much, but it is enough to notice a difference. If you’re below this range you’re really going to have a rolly feeling tire under you. And if you’re above this range you’re going to sacrifice traction and have a very hard, stiff feeling tire.

For 60 and 80cc bikes the tire pressure range is around 12 pounds for both front and rear tires.

Temperature and altitude will also greatly affect tire pressure. Tires begin to loose pressure in as little as 3 days, so check your tires often. And make sure you have an accurate tire gauge. Most cheap gauges can be off as much as 4 pounds.

Well, that sums up all the important adjustments that you need make in order to get the most out of your iron horse, whether it’s a stocker or a full on modified mount.

Think about it… You could have the best-modified bike in the world, but if just one of these adjustments were way off, a stock bike that is adjusted right, would be far better. Get to know and understand your bike, and learn and test these adjustments. It can be interesting and fun, and best of all it does make a big difference in your performance.

Desire - "Where there is a will there is a way, is an old and true saying. He who resolves upon doing a thing, by that very resolution often scales the barriers to do it, and secures it's achievement. To think we are able is almost to be so. To determine upon attainment is frequently attainment itself".

Gary Semics Motocross School & Videos - www.gsmxs.com

Published on: 2006-03-06 (366 reads)

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