The Internet Karting Glossary Definitions: S-Z

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Safety wire
A stiff wire which is used to secure screws and pins on the kart, so that they will not fall off during the race. Typically, a screw would have a thin hole drilled through it at the end, which extends past the nut. The safety wire would be threaded through this hole, so that the nut could not come off anymore. An alternative to the safety wire can be a cotter pin.



Scales

Used to measure the weight of the kart. With several scales, or one scale and more effort, the proper weight distribution of the kart can be measured. Also, the kart (with driver) will be placed on the scales during tech inspection.



Scrub

When a tire does not rotate in the same direction or with the same speed as the kart moves, it scrubbs over the road surface. When the kart is understeering the front wheels are 'scrubbing off speed'. Since the rear axle in a kart does not have a differential, the inside rear tire will scrub as well. See also frame.



Seat

The seat on a kart should be tight, so that you can sense every motion of the kart with your body. Also, it will prevent you from bouncing around uncontrollably in the curves, since a kart does not have any seat belts. Pedded seats are nice, but not a necessity. By moving the seat around or up and down, you can significantly change the handling of the kart, since you will have achieved a different weight distribution. The seat is mounted to the kart via seat struts.



Seat struts

Components that mount the seat to the frame of the kart. The placement and number of struts can alter the handling of the kart by changing the stiffness of the overall structure (which alters the flexing ability of the frame.



Seating position

The seating position greatly affects handling (see seat). But extreme seating positions will also impede the drivers ability to control the kart comfortably at all times. Turn the steering wheel and make sure that at no time the arms are fully extended. Also, when depressing the pedals, the knees should at no point be fully stretched.



Seizing

A different term for 'getting the engine stuck'.



Sending unit

The sending unit is pushed over the end of the spark plug which is accessible from the outside. The spark plug cable is attached to the plug via the sending unit.



Setup

A kart's setup is the set of all variables of the system, i.e. the setting of all those things which can be modified on the kart (which is a lot). A different setup may induce different handling characteristics, or may be suitable for different track conditions. E.g. a kart may have a 'rain setup' and a 'dry setup'. The setup may also be different for different drivers. Some of the things which make up a specific setup are: rear- and front track, seat position, weight distribution, etc.



Shifter

A type of kart that has a manual transmission, usually derived from a motorcycle design. It is usually a 5 or 6 speed transmission. Since with a manual gearbox the driver can keep the engine in its optimum RPM range, shifter karts tend to be (much) faster than clutch karts.



Shoes

High-top shoes (covering the ankle) must be worn by a kart driver. Even though special karting shoes are offered, many drivers wear either high-top running shoes or wrestling shoes. The sole should be thin, so that your feeling-sensitivity is not reduced. Abresion resistant shoes are recommended.



Side panels

A piece of body work mounted to the nerf bars. Good place to mount the side number panel.



Side pods

A piece of body work mounted on the side of the kart, between the wheels. The mounting hardware is somewhat more complex than the nerf bars used to mount side panels.



Situp

The variety of kart used on short-track speedways and sprint tracks. As compared to laydowns, the driver sits more or less upright in these kinds of karts. This is acceptable, since on these shorter tracks aerodynamics are less of a factor.



SKUSA

Shifter Kart USA, which is a new governing body for shifter karts only.



Slave cylinder

The slave cylinder is mounted 'around' the brake disc and contains the calipers with the brake pads mounted to them. The slave cylinder is connected to the master cylinder via the brake hoses. It converts the hydraulic pressure transmitted through the hoses by the brake fluid into mechanical pressure, by forcing the brake pads down onto the rotating surface of the brake disc.



Slipping

When the clutch in a clutch kart is disengaged because the RPM are below the stall speed, the clutch is said to be 'slipping'.



Snap ring

A small ring with about the same diameter as the rear axle which will be snapped into a groove around both ends of the axle. It is there to prevent accidental loss of wheels and other necessities.



Snell

See Helmet.



Software

The right software can help the racer to analyze the lap times and other testing data. The Lap Tracker is a fine example of professional and affordable lap time analysis software.



Space chain

A popular variety of chain which combines certain elements of the #35 chain and the #41 chain.



Spacers

Flat-sided, light metal rings of different thickness, which are positioned inside of the front wheels on the spindle. By varying the number of spacers, one can set the width of the front track of the kart, which in turns affects handling.



Spark plug

A little device sitting in the middle of the cylinder head, which generates an electric spark when the piston has reached the top point, and the air - fuel mixture is compressed. The spark will ignite the air - fuel mixture which will rapidly burn off. This in turn will drive the piston down again. Spark plugs are relatively cheap and should be checked often and replaced if necessary, typically every 4 to 5 races. A special spark plug tool is used to remove the plug. The temperature sensor is located around the base of the plug. The sensor to measure the RPM is attached to the spark plug cable. The spark plug cable is attached to the plug via the sending unit. The size of the gap at the bottom of the plug varies depending on the kind of spark plug and should be the gap specified by the engine manufacturer.



Spark plug tool

A special tool used to screw/unscrew the spark plug to/from the cylinder head. It looks like a long socket from a socket wrench.



Spec

Various governing bodies may require certain components of the kart (e.g. tires, engine) to fit certain 'specifications' (specs). The tech inspection will try to ensure that all components are according to spec. Some open classes do not bother about such technicalities.



Speedway

Racing on oval tracks, which requires its own set of driving techniques and kart setup. Oftentimes offset karts are used in this type of racing. There are dirt ovals and asphalt ovals.



Spindles

The 'axles' of the front wheels. They are connected to the steering column through the tie rods. The front wheels are mounted on the spindles. The spindles themselves are mounted to the frame via the kingpin. The part of the spindles to which the tie rods are connected is called the spindle arm or pitman arm.



Spindle arm

Part of the spindle. The tie rod is connected to the end of the spindle arm. The spindle arm sticks out backwards in a steep angle from the actual front 'axle'. Also called pitman arm.



Sportsman can

A special type of exhaust which is used in the sportsman class. It will reduce the horse power of the KT-100 the most of all the typical exhaust systems. It looks like short, stubby soft-drink can, with three small holes in it.



Sportsman class

The class of karting which uses the KT-100 engine and the sportsman can type of exhaust. Since this type of exhaust is very restrictive, the karts in this class tend to be relatively slow (compared to other KT-100 classes). Since therefore the wear and tear on the kart is less and since this class often also mandates certain hard (longlasting) tires, it is the preferred beginners class. There even is the novice sportsman class, a specially for beginners.



Sprint

A kind of kart racing which utilizes smaller road courses, with turns to the left and right, as compared to speedways. Sprint courses require different setup than the ovals used in speedway racing. Sprint karts are of the situp variety. Races usually last only a few minutes, with a pre-determiend number of laps. See also: enduro racing.



Sprocket

There is a sprocket mounted to the crankshaft of the engine, which is typically quite small and is also called the drive sprocket. A much larger sprocket is mounted to the rear axle, is connected to the drive sprocket via the chain and is also referred to as the driven sprocket. The size ratio between the two is called the gear ratio. Since this ratio can be easily modified by exchanging the sprocket on the axle, these sprockets and/or ratios are also referred to as gears. You can choose between single-piece sprockets, which and two-piece, or split sprockets. In order to change the single-piece sprockets, you will have to unmount the axle, the split sprockets can be changed while the axle is mounted. Thus, many prefer the split sprockets, but some claim that single-piece sprockets run more true.



SSX

A different name for the super sportsman can.



Stagger

The size dfference between two opposite tires, i.e. between the two rear tires or the two front tires. Stagger is only used for oval racing.



Stall speed

The engine RPM that an automatic clutch tries to engage at. See slipping.



Stand

A contraption on which you can place the kart in order to work on it. Often, the stand is foldable and might have wheels which allow you to roll the kart to the starting grid.



Starter

A kart does not have its own starter engine, like a regular car. Rather, like in many race cars, it uses an external starter. This is typically an electric motor, mounted together with a car battery, driving an axle which can be stuck on the outside end of the crankshaft of the engine. Pressing the button on the starter will turn over the engine. Some 4-cycle engines can be started by hand, however.



Starter nut

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Starting grid

See grid.



Steering column

The steering wheel is mounted on the column, which is mounted through a joint to the kart frame on the other end. The tie rods are connected to the steering column, such that rotating the steering wheel will move the front spindles. A steering column may or may not support Ackerman steering. Also called steering shaft.



Steering shaft

Another name for the steering column.



Steering wheel

The round thing you hold in your hands and rotate left or right to steer the kart. Duh! A padded steering wheel is preferred, since otherwise the vibrations can really get to you. Various displays are typically mounted to it.



Stickyness

The stickyness of a tire is determined by its compound. See tires.



Stiffness

A kart frame is designed to allow flexing, a very important property of the frame. The stiffness of the frame is a measure for how easily it can be flexed. Fast classes which race with sticky tires require a stiffer frame than slower classes which utilize harder tires. Stiffness can be changed by the setting of the torsion bars and the thickness of the rear axle.



Stuck

A state of your engine which will make you pay a lot of money to an engine builder to get it fixed again. But seriously, if the engine gets too hot, e.g. by running it too lean, the piston may get stuck inside of the cylinder. You will probably have to bring the engine to the engine builder for repair. To avoid the engine getting stuck, make sure it does not get too hot. Watch the CHT and adjust the needles accordingly.



Suit

The karting suit is an important safety equipment. It is typically made of an abresion resistant material, e.g. Cordura. Oftentimes it has padding on elbows and knees, since it is designed to protect the driver in case he/she is flung out of the kart and comes crashing to the ground. Karting suits do not need to be made from Nomex, the fire resistant material used for other racing suits, since the driver will not be stuck in a burning vehicle. To get an idea about the pricing of really good karting suits, go to the LEAF Racewear homepage.



Sump

1. The bottom portion of the engine which houses the crank case. Towards the top, the cylinder extends from it.
   
2. Recessed area in the bottom of the fuel tank to improve consistancy of fuel flow when the fuel level is low.
   



Super can

A different name for the super sportsman can.



Super sportsman can

A kind of exhaust used in the super sportsman class of karting. It is similar to the sportsman can, but allows the engine to generate more horse power. Also called SSX.



Super sportsman class

The class of karting which uses the KT-100 engine and the super sportsman can type of exhaust. Since this type of exhaust is quite restrictive, the karts in this class tend to be slower than in the pipe class. Since the beginning karter can graduate from sportsman class to super sportsman by just exchanging the exhaust, this class is also very popular.

Yamaha
Manufacturer of the most common karting engine, the KT-100.