Technical Explorations of ideas related to karting

How to Set Up Dual Eccentric Pills on your kart

How to Set Up Dual Eccentric Pills on your kart

In outdoor karts Eccentric Pills are used to adjust the caster and camber of go karts. Indoor karting will eventually lead you to driving and setting up your own outdoor kart. This article examines 16 point eccentrics. Similar rules should apply to 4, 8, 12 point eccentrics.

Eccentrics have an offset center point allowing you to offset the kingpin as you rotate the top and bottom pills. Not many people really understand them, and the information on the internet is scarce. I will try to fill in the blanks.

 Typically these pills are considered to be Caster and Camber adjustments only, but they are actually much more than that as you will see, and they can seriously mess up a kart or bring it magically into alignment. 

 For this reason it is recommended that if you are fairly new, you should only touch your pills in the event that you have a serious problem and need to fix it, because as a new driver your biggest gains are going to come from mastering the line and refining your driver. Pill set adjustments only really start making a difference in lap times when the driver is consistently within .500 of the fast lap time. 

So as a rule of thumb, get your driver right first, and worry about the kart second unless it is totally jacked up and you need to fix a bent and broken kart.

There are two ways to use them.

 1. Zero pills where you have a center pill on the bottom, and then use only one on top (or bottom). This allows for an easier to conceptualize modification of your camber and caster.

 2. Dual Eccentrics top and bottom. This is my preferred way of using eccentrics and the most confusing so we will discuss this method.

 Throughout this guide I will use the following terminology to describe pill positions.

 If you look at the picture above, I show a 16 point eccentric pill set. Note that the northmost position is labeled as #1 and the positions go clockwise to #16. 

 When making pill adjustments we will usually need to make changes to all 4 eccentrics on the LF and the RF top and bottom so I will refer to these as LF[1:1] and RF[1:1] for left front and right front.

 Left Front represents the kart from the drivers perspective so it would be the front wheel closest to his left hand.

 The first part of the number (seen as “[1:” in the [1:1] ) represents the top pill position and the second part of the number (seen as “:1]” in the [1:1]) represents the bottom pill position.

 So if you see RF[2:16] This means to rotate the top pill counter clockwise from position #1 and to place the #2 hole in the place where the #1 hole used to be. So rotate 1 click CCW. Then rotate the bottom clockwise one click to move the #16 hole into the #1 position. LF[1:1]RF[1:1] would mean to set to North Neutral position where both top and bottom are set to position #1.

Note also that the #1 position is furthest from the center hole, and that the center hole is off center. This allows for a total displacement of each kingpin of 3 mm in the north/south axis and 3mm in the east/west axis. If applied equally to both wheels that means we have a total potential displacement of 6mm to the track width and relative length of the kart. This is enough of a range to create a serious displacement of the kart, so be careful.

Now if for example if we were to rotate through the 16 neutral positions from say [1:1] to [2:2] it would have the effect of moving the king pin forwards, upwards and outwards all at the same time. 

Now you can’t move to [2:2] on both sides of the kart and remain balanced because you would be moving both sides in the same direction. Instead if you move the left front to [2:2] then you must move the right front to [16:16]. Now your track width has moved a total of 0.75mm and your kart wheel base has become 0.75mm shorter. Meanwhile your caster and camber has stayed the same, while your ride height raised just slightly.
For now that is inconsequential, but if you had to repair or adjust a kart that had lost it’s squareness, this is a great tool to have in the toolbox. You can adjust your squareness, without affecting your camber and caster and dial out tendencies to pull left and right, which can also remove drag from your straightline speed.

Finding neutral.

Dual Eccentrics allow for a total of 256 possible settings (16 top and 16 bottom). Of these 256 possible settings, 16 of them are actually neutral. Neutral means they do not try to change the caster or camber. They are the positions where the top and the bottom exactly line up.

This table shows the 16 neutral positions for the Right Front (RF) and how they affect ride height and track width in Millimeters. It also shows the corresponding LF setting for neutral and gives an estimate for the total width displacement of that position.

In this diagram red shows the bottom pill setting and black is the top. You can reverse this for the left and right, so on the left side the red would be on top and black on bottom.

[2:16]-0.7502.250[16:2]00.000        -1.125-0.375+2.625

From this you can see that you can make height, width and length adjustments just using the pills, which can be very handy for straightening out a bent kart.

Using Neutral Quadrants. 

I find the easiest way to think of the neutral positions as starting points, and use the North, West, South, East most position as quadrant starting points depending on what you want to achieve.

North Quadrant – How to adjust Camber only….

Note in this picture, North Quadrant (Q1) starts at position[1:1] and we would place both sides of the kart into north Quadrant. This neutral position is great if you want to make camber adjustments. Because moving the top pill +/- 1 click will rock the king pin top left and right. Then you would make equal counter movements on the bottom to keep the king pin centered and to retain your caster. Note that the following settings all have the same caster. Note that if you number all your pills from 1 to 16, and then place them together on top and bottom, you can then make your camber adjustments by rotating both top and bottom the same amount. IE 1:1, 2:2, will actually move the top and bottom in opposite directions. Because of this the width adjustment top and bottom cancels each other out, and the kingpin rocks left and right on a center point.


If we continue instead of negative camber adjustments, we make positive camber adjustments.


As you can see, there are two settings that will rock the kingpin in or out, but one of them has a higher / lower ride height than the other and one can make the kart longer or shorter..

East Quadrant is achieved by going to [13:5]. This has the effect of moving the center axle holes into the left most position. Note if we were to use East Quadrant on one side, then we would have to use West Quadrant on the other side. But if we use North or South Quadrants then we use them equally on both sides.

Effect on width. Note also that if we use East Quadrant on the RF and West Quadrant on our LF then we just made our total kart length 1.5mm shorter than North Quadrant and also decreased our front track width by a total of 3mm. We have also raised our ride height by 1.5mm. In effect we have raised our center of gravity and should give the kart more bite and downforce. We have also reduced scrub radius so this should make the kart more eager to rotate.

East/West Quadrants – How to adjust Caster Only.

East/West  Quadrants are where we would go to make micro caster changes. From this position we can rock the kingpins forward and backwards. Starting at RF[13:5] we get..


Checking and adjusting squareness using eccentrics.

If you only tweaked one side of the kart, then you would make one side longer than the other. You would also need a longer tie rod on one side of the kart and you would need to re-adjust all your steering alignment. 

You could use the pills in this way to square up a kart that does not measure straight. Karts get bent all the time, typically a hit in the rear will bend the longitudinal struts that hold the rear bearing cassettes. These are made to be flexible like shock absorbers, but they also hold the bumper so if they get hit at an angle they are at risk of bending. When they do, your kart will show one side gets longer than the other, or one side is higher than the other, and it will start to pull left or right. Especially if you take your hands off the wheel. You can either get it on a rack or scales, and then bend it, or make emergency repairs using pill adjustment. 

Sometimes even after getting the wheels evenly flat, you are still bent with one side longer than the other. You can then use the pills to dial it back in.

 First to check straightness, you would take a magnet and place it on the front center of the rear axle, then get a metal tape measure and place it on the magnet to lock it to the front of the rear axle. 

 Next measure the distance from axle to kingpin top center on each wheel. Note that when you change your magnet to the other side of the axle that you want to make sure to be the exact same distance from your bearings to the magnet on each side.

 To be square you want the distance to be identical.
Now check the distance to kingpin bottom, you also want these to be identical. You will find here if your steering yoke has been bent and tweaked.
If you are short on one side you can now use a neutral pill setting to make each side longer or shorter.

In the same way your steering tie rods should be the same length when at dead center. If they are not, you can use your neutral pill settings to lengthen one side of your kart. Even though this can have the effect of changing ride heights, width and length, I have found quite often that these adjustments actually bring all in line together as you would need. Something to do with the fact that the kart was probably in line at first, and after the bend, the height, length and width were all affected.

Which neutral to use?

Whether you start from North Quadrant, South Quadrant , East or West, doesn’t really matter in the scheme of things. And how you choose to go is up to you.

Some things to keep in mind though when dialing in the pills.

Lower ride height will lower your center of gravity and tend to give the kart more lateral force, less grip and make the front weight seem lighter under load. It can slow the weight transfer speed like taking a bar out might do. And it can help to reduce hop in a high grip situation. The lower ride height settings also lengthen the wheelbase, so they contribute to slower weight transitions and smoother slower rotations.

Higher ride height will raise your center of gravity and can help with an entry push giving you more bite on entry. It can help to fight a slide in the rear on exit, due to over steering. It can give you more grip in low grip situations or the wet. The higher ride height also makes your total length shorter, making your kart more darty and wanting to rotate faster. Which can make the rear more sensitive to slide. It will speed your weight transfer up.

How does weight affect go kart speed?

How does weight affect go kart speed?


Many years ago I had to coach a heavier driver with the goal of helping them qualify for the higher powered 9HP karts at Sykart. This would allow them to get out of the 6HP karts and drive the faster 9HP karts. As part of that mission I added weight to my own kart so we could both roll at around 350lbs. Now normally I roll around 200lbs so this was a great opportunity to see exactly what effect an extra 150lbs had on my lap times.

Well as expected, it totally killed my speed. What was unexpected was just HOW MUCH it killed my speed. We quickly realized that Sykarts qualification system that issues a handicap for lighter drivers was disproportionately biased towards lighter drivers. So on behalf of my student I had to go through the exercise of proving it, and had to try and convince Sykart to adjust their weight based ranking system.

Sykart did adjust their qualification system after this analysis.

So the rest of this document is basically the analysis and study as I looked into exactly how weight affects the speed of a go kart and lap times.

If you’ve ever raced at a go kart track, you’ll quickly realize there is something about weight that either helps you or hold you back. I’ve seen many debates about weight, some believe it’s an advantage to weigh more or that being light is a disadvantage. I must tell you, I’m not in that camp. Adding weight will kill your speed, and in this article we’re going to look at how I applied Newtons Kinetic Formulas to explore the effect of driver weight on lap times at Sykart Indoor Karting track during one winter season.

Newtons formulas tell us that any movement requires energy made up of the combination of weight and speed. If something weighs more then it needs more energy to travel at the same speed as something that weigh less.

You might want to apply some of these tricks yourself on your track because just going through the process will give you a better insight about your situation.

How to analyze exact sector times on your go kart track. 

The first step was to find a Google Maps satellite image of the building that holds the track. Next was to use a track map and try to scale it exactly to the proportions of the building.

Next I created a scale image in photoshop then imported the image into Geogebra and scaled the image so that 1 unit = 1 meter in real life. This allows very precise measurements of arcs and line segments and you can start to get an idea of the total length of the track and each of its segments.

Here are estimated measurements of the approximate fast line, superimposed over a scale model of the building, taken from Google Earth satellite picture of Sykart

Next I took Go Pro videos of the track, and stepped through the videos one frame at a time. This allowed me to count the number of frames through each section and gave a measurement of the speed in meters per second.
One frame of a 60 frame per second video is 1/60th of a second. By observing the wheels next to marks on the track and by noting hand and foot movements you can get fairly accurate estimates of the time spent in corners and on straights. As you know what the lengths of these sections are you can estimate your speed using time/distance.

By mapping the speeds of each section onto a spreadsheet, I was able to create these charts.

The following charts take into account an analysis of the driving line, using GoPro Video to find the distances and speeds through each section, and then measuring the total amount of acceleration and deceleration per lap. (see Chart 1). The calculations use a driver weight baseline of 160lbs and show how +/- 10lbs affect lap times.

Chart 1: Speeds and G forces of the turns were calculated, and adjusted for driver weight.

This chart shows the range of velocity in m/s, from an average Sykart lap where there are 3 deceleration / acceleration zones, two sharp brake zones and a two phased brake zone at around 18 seconds into the lap.

Creating Time / Weight Charts
Using Newtons kinetic formulas, based upon the energy required to move the mass of driver and kart, we can calculate the amount of time it takes the power of your engine to reach maximum velocity. This allows us to build a chart of expected lap times given the weight of the driver.


Kart weight = 119 kilos (taken from scales)
6.5 hp         = 4847.049168 Joules per second Power Capacity of Engine
9.0 hp         = 6711.298848 Joules per second Power Capacity of Engine
(Sykart has 2 different kart types, a 6.5hp and a 9hp model)


k = mv²/2                    Where k= kinetic energy in joules, m=mass in kg, v= velocity in m/s

1 hp                          = 745.699872 Joules/second

Whats a good time?

Driver lbs6Hp9 HpAbove Avg 6.5Good 6.5ExpertGodlyExpert 9 Hp

Becoming 9HP Qualified.

At the time of writing, the Sykart qualification times (given weight) to drive the higher powered karts are. They have created this system of weight brackets to simplify the qualification process. Its actually a very cool setup that lets newer drivers develop their skills in the pursuit of the higher powered club karts. It also makes some allowance for the speed handicap that extra weight creates.

0 – 150lbs = 30.200 lap times or lower
151 – 200lbs = 30.500 lap times or lower
201 – 250lbs = 30.750 lap times or lower
251 – 300lbs = 31.000 lap times or lower
300 +       = 31.250 lap times or lower

What the calculations tell us is that if Qualification Times @ 160lbs = 30.500 then the weight adjusted equivalent time for a driver at 250lbs should be 30.500 + 0.950 = 31.45, but because of the Sykart Bracketed Weight Class System, the 250lb driver is actually required to beat 30.750. So there is a relative handicap to the heavier driver of 0.700 seconds. That is, for the 250lb driver it is like being 160lbs and having to hit a 29.8 in order to qualify instead of a 30.5.
While this is a little bit biased and possibly unfair, it should also be noted that beating these times are incredibly easy even if you have average skills.

For a 300lb driver an equivalent weight adjusted time would be 30.500 + 1.477 = 31.977 seconds, etc. But they are expected to hit under 31.000, more than a .9 second handicap difference. This is like being 160lbs and having to beat a 29.300.

The driver at 140lbs would have an equivalent adjusted time of 30.500 – 0.211 = 30.289, so they also are at a little disadvantage to the 160lb driver, but only by about 0.200 so they are not hurt as badly as the heavy driver but they are still like a 160lb driver who has to hit 30.300 instead of 30.500, so there is some handicap.

And a 210lb driver would be 30.500 + 0.528 = 31.028, so they are a little closer to the asked time of 30.750. A difference of 0.278. So it is like being 160lbs and having to beat a 30.200.

The current qual times favour the driver between 150 to 170lbs, and become increasingly more difficult for the drivers above and below this range, particularly those above this range.

While these times are achievable, it must skew the skill levels of the 9hp qualified drivers and the volume of drivers who become qualified must disproportionately skew into the 150lb to 180lb range.

Personally I have found that running 30.3’s at 200lbs is easily achievable in all karts, where you are reasonably on line, under most track conditions and under race conditions I would expect to run in the low 29’s.

30.3@200 is a weight adjusted time of 29.878 @160 

Currently we are asking a 200lb driver to run 30.5 – 4.22 = 30.078 weight adjusted times.

But what is the equivalent time to a 330lb driver?

30.078 + 1.700 = 31.778 

But currently they are expected to run below a 31.250

The following chart raises the bar slightly to 30.3 for a 160lb driver, then shows a relative qual time for all weights on the blue line. This is the suggestion of where Sykarts Qual times should actually be.

The red line is an Elite driving time, for the 6.5HP karts which is in line with best times of drivers winning league races.

The orange line is an Elite Driving time for 9HP karts, given top league finishes.

Isn’t interesting how differences in weight create a linear handicap?

Here is a Table for Qualification, and Elite 6.5HP and 9HP Times. If you can hit the elite times here then you are in a very special class and could compete nationally. The Qualification times are where you would want to be if you are shooting to be amongst the top drivers.

Weight (lbs)Qualified 6.5Elite 6.5 TimesElite 9 Times
Time Lost to Weight
Driver lbsLow 5m/sHigh 10 m/sJoules to climb6.5Hp9Hp6Hp9 Hp

The chart above basically confirms the old theory that for every 10lbs you lose 0.100 seconds per lap.

Possible errors: It doesn’t take into account things like clutch slippage and extra binding in slow corners to heavier drivers, so heavier drivers might actually have even more of a penalty, consider this best case scenario..

If you know driver weights then you can adjust their lap times into a baseline time. If a driver is 230lbs in a 9hp kart, then you subtract 0.533 from their time and you get the 160lb driver time. If a driver is 140lbs in the same kart then you add 0.152 to their lap time.

How much time it takes to go from dead stop to vmax at 11m/s, given weight of driver

Driver lbsDriver+kart lbsDriver KilosDriver+kart Kilosjoules at 11m/s6hp T to vMax9hp T to vMax

So at the end of the day Sykart Adjusted their timing requirements and made it easier for heavier drivers to get into the 9HP club up from the 6HP club.

On most tracks I have visited 10lbs will cost you about 0.100 seconds per lap, this is the result of the cumulative effect of the acceleration zones. This is the easy rule of thumb, but if you have more or less corners this could obviously vary quite a lot.

Weight handicaps are real, and for this reason most well run indoor karting leagues will have strict weight requirements and use ballast to equal things out.

This could be a good thing, because the easiest way you can improve your lap times is to lose some weight. Managing your weight becomes a very important part of the sport and hobby of indoor karting. If you are struggling with your weight, you might consider a keto diet and intermittent fasting (I’ll discuss this elsewhere). Keto is insane at stripping the weight off, you can easily strip 0.100 off your lap time every 2 weeks.

I have an article here on site that talks about what you can actually do if you are a heavier driver.

Meanwhile good luck, and I’ll see you on track.