Karts are made up of various components.
The chassis are made of steel tube. There is no suspension therefore chassis have to be flexible enough to work as a suspension and stiff enough not to break or give way on a turn. Kart chassis are classified in the USA as 'Open', 'Caged', 'Straight' or 'Offset'. All CIK-FIA approved chassis are 'Straight' and 'Open'.
- Open karts have no roll cage.
- Caged karts have a roll cage surrounding the driver; they are mostly used on dirt tracks.
- In Straight chassis the driver sits in the center. Straight chassis are used for sprint racing.
- In Offset chassis the driver sits on the left side. Offset chassis are used for left-turn-only speedway racing.
The stiffness of the chassis enables different handling characteristics for different circumstances. Typically, for dry conditions a stiffer chassis is preferable, while in wet or other poor traction conditions, a more flexible chassis may work better. Best chassis allow for stiffening bars at the rear, front and side to be added or removed according to race conditions.
Braking is achieved by a disc brake mounted on the rear axle. Front disc brakes are increasingly popular; however, certain classes do not allow them.
Professionally raced karts typically weigh 165 to 175 lb (75 to 80 kg), complete without driver. Avanti, Tony Kart, Trulli, Birel, CRG, Gillard, Intrepid, Kosmic, Zanardi or FA Kart are a few well known examples of the many European manufacturers of race-quality chassis. Margay is an American company producing kart chassis.
Amusement park go-karts can be powered by electric motors or 4-stroke engines, while racing karts use small 2-stroke or 4-stroke engines.
- 2-stroke kart engines are developed and built by dedicated manufacturers. Comer, IAME (Parilla, Komet), TM, Vortex, Titan, REFO, Yamaha and Rotax are manufacturers of such engines. These can develop from about 4 hp to 7 hp for a single-cylinder 60 cc unit to 90 hp for a twin 250 cc. The most popular categories worldwide are those using the Touch-and-go (TAG) 125 cc units. 100 cc 2-stroke kart engines can run in excess of 19,000 rpm while the new 125 cc KF1 engines are electronically limited at 16,000 rpm. Most are water-cooled today; however, previously air-cooled engines dominated the sport.
- 4-stroke engines can be standard air-cooled industrial based engines, sometimes with small modifications, developing from about 5 to 20 hp. Briggs & Stratton, Tecumseh, Kohler, Robin, and Honda are manufacturers of such engines. They are adequate for racing and fun kart applications. There are also more powerful four-stroke engines available from manufacturers like Yamaha, TKM, Biland or Aixro (Wankel engine) offering from 15 hp up to 48 hp. They run to and around 11,000 rpm, and are manufactured specifically for karting. Those are used in some National Championship classes like the two-strokes.
Listen to 2-stroke kart engines - recorded at the 2006 World Championship in Angerville - France
Karts do not have a differential. The lack of a differential means that one rear tire must slide while cornering; this is achieved by designing the chassis so that the inside rear tire lifts up slightly when the kart turns the corner. This allows the tire to lose some of its grip and slide or lift off the ground completely.
Power is transmitted from the engine to the rear axle by way of a chain. Both engine and axle sprockets are removable; their ratio has to be adapted according to track configuration in order to get the most of the engine.
In the early days, karts were direct drive only, but the inconvenience of that setup soon led to the centrifugal clutch for the club level classes. Dry centrifugal clutches are now used in many categories (Rotax Max is one example) and have become the norm as the top international classes have switched to 125 cc clutched engines as of January 2007.
Wheels and tires are much smaller than those used on a normal car. Wheels are made of magnesium alloy or aluminum. Similar to other motorsports, kart tires have different types for use appropriate to track conditions:
- Slicks for dry weather. In international level racing these are some of the softest and most advanced tires in motorsport. Some car tire manufacturers, such as Bridgestone and Dunlop, make tires for karts; there are also specific Kart tire manufacturers, for example MG, MOJO, and Vega. Kart tires come in many different compounds, from very soft to very hard.
- Rain tires or wets for wet weather
- Intermediates for damp or low traction conditions. Sometimes worn rain tires are used.
- Special, such as spiked tire for icy conditions, or cuts for high grip dirt/clay speedways. Cuts are modified slicks using a lathe to optimize handling while spiked tires are slicks with screws through them.
Tires are sometimes prepared with special solvents to soften them and increase grip, however this is banned by many racing organizations. These solvents typically affect the behavior of the tire temporarily and are most often destructive to the rubber. The tires can support cornering forces in excess of 2 G (20 m/s²), depending on chassis, engine, and motor setup.
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