OKN-Junior

Background (1962–2022)

The Commission Internationale de Karting (CIK-FIA) was founded in 1962 as a sister commission to the CSI, later known as FISA and the FIA, to govern international kart racing competition.^[1] It hosted the first CIK-FIA World Championship in 1964, which has been held annually since.^[2] The CIK-FIA began its homologation of distinct classes in the discipline in 1974, when the first 125 cc gearbox category was created for the European Championship: Formula C (FC).^[3] The 100 cc direct-drive category was clarified in 1976, when Formula Europe was introduced to control technical evolutions and costs.^[4] The direct-drive classes were adapted in 1981, when the 135 cc Formula K (FK), 100 cc Intercontinental A (ICA), and Junior Intercontinental A (ICA-J) were introduced to the World Championship, European Championship, and World Cup, respectively.^[5] Component technical approvals have been mandated by the CIK-FIA since then.^[6] The 250 cc superkart category received World Championship–status in 1983, having reached international competition as early as 1976.^[7][4]

Junior direct-drive classes have evolved substantially since 1981. ICA-J was introduced to the European Championship in 1989 and remained at the World Cup until 1996, where notable winners included two Formula One World Drivers' Champions: Alain Prost (1973) and Fernando Alonso (1996).^[3] In 2007, it was replaced by 125 cc KF3 regulations, later known as KF-Junior (KF-J).^[8] The KF era was marked by decreasing entry figures as costs for competitors spiralled due to the presence of manually-controlled front brakes, sophisticated cable systems, and fragility of components.^[9] It was eventually replaced by OK-Junior (OK-J) in 2016, which—following iterations by the CIK-FIA—offered improved performance, reduced weight, and increased competition by eliminating the centrifugal clutch, complex cabling, and starter motor, with later reductions to the rev limiter and exhaust valve; after six years, it was deemed ready to expand into national championships.^[9][10]

Creation

Plans for a new minimal-cost direct-drive category were submitted by the CIK-FIA to the FIA World Motor Sport Council in 2022; they were approved in July, with the CIK-FIA confirming the "OK-N" category would host its inaugural World Cup in 2024.^[11] The "N" suffix is an initialism of National, reflecting that qualification for the World Cup would be determined via national events.^[12] Described as a "hybrid" between the OK and OK-Junior categories, OK-N engines were first tested in the final round of the European Championship that year at Franciacorta.^[13]

OKN-Junior (OKN-J) was unveiled alongside the senior category, utilising a lower rev limiter to increase reliability and a higher minimum weight to reduce costs and bolster accessibility; additionally, CIK-FIA events were to operate as a single-manufacturer discipline, with one brand of engine, chassis, and six option tyres.^[14] OKN-J uses an identical design to the OK-N engine, with the only technical difference being a 26 mm (1.0 in) flange on the exhaust.^[15] ACI Sport carried out further tests at Sarno and Cremona, in preparation for both categories' debuts in the Italian Championship, where they would serve as a gateway from Mini Gr.3 to OK.^[16][14]

Competitive beginnings and World Cup debut (2023–present)

The class debuted internationally in 2023, featuring in the Champions of the Future Academy Program (COTFA), WSK Euro Series, and WSK Final Cup.^[17][18] Its debut was postponed from February to June, removed from the WSK Super Master Series, and had only one entry in the WSK Open Series, which Kartcom opined was "more a casting error than a failure of the new concept".^[18] It featured the following year in both the Andrea Margutti Trophy and Trofeo delle Industrie.^[19] The Road to the World Cup, organised by ACI Sport, was held at Franciacorta as a support race to the 2023 World Championship and won by Jesse Phillips.^[20]

Qualification for the inaugural World Cup in 2025 was decided via national championships in several countries, as well as the podium of the African Cup, for a total of 72 drivers. Each National Sporting Authority (ASN) hosting a national championship were given three entries, with the exclusion of all European Championship entrants.^[21] The Arrive & Drive World Cup was inaugurated that year, featuring Vortex engines derived from OKN-J with centrifugal clutches.^[22] In the Italian Championship, average entry numbers in OK-N and OKN-J increased from 70 in 2023, to 90 in 2024, to 120 in 2025; a record 190 entered the 2025 Cremona round in preparation for the World Cup.^[23] With the increased demand from ASNs, the World Cup increased from 72 to 90 drivers.^[24]

Technical regulations

There are 16 main technical features of the OKN-J regulations:^[25]

• 125 cc, direct-drive, single-cylinder, two-stroke, mixed-lubrication, reed valve engine;
• Single cooling circuit for the crankcase, cylinder, and head;
• Exhaust port with maximum angle of a 194°;
• Combustion chamber with a minimum volume of 10 cc;
• Mandatory decompression valve;
• Monotype power valve;
• Maximum lubricant–fuel mixture of 4%;
• 30 mm (1.2 in) floating chamber carburettor or 24 mm (0.94 in) butterfly carburettor, decided by the governing ASN;
• Two-duct 23 mm (0.91 in) intake silencer;
• Digital ignition system with rev limiter of 15,000 rpm;
• Monotype exhaust with 26 mm (1.0 in) flange and silencer;
• Type-219 chains and sprockets;
• Radiator with one cooling circuit;
• 2WP B2 or BRKR single rear brake with hydraulic control;
• Prime tyres, medium gum compound;
• Minimum weight of 145 kg (320 lb) with driver, 70 kg (150 lb) without.

The sole differences to the technical regulations of OK-N are the 10 kg (22 lb) minimum weight reduction and the exhaust flange.^[25] Engines, chassis, bodywork, brakes, and tyres are subject to the homologation and approval system operated by the CIK-FIA.^[6] Each year, the specific tyres and fuel for use in competition are selected after a call for tenders.^[26] With elimination of the clutch, electric starter, battery, and electrical wiring, TKART described the OKN-J regulations as being "as simple as it gets".^[10]

World Cup specification

The Road to the World Cup at Franciacorta in 2023 used Group 1 engines and chassis, and Vega XH3 option tyres.^[27]

More information Year, Circuit ...

Year	Circuit	Engine	Chassis	Tyres	Ref
2025	Cremona	To be determined

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Arrive & Drive World Cup specification

The Arrive & Drive World Cup features an arrive-and-drive format using OKN-J engines fitted with a centrifugal clutch.^[22]

More information Year, Circuit ...

Year	Circuit	Chassis	Engine	Tyres	Ref
2025	LYL International	Kosmic	Vortex	V	[22]

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Engine manufacturers

As of 2025, six engines are homologated for use in OKN-J by the CIK-FIA, manufactured by Modena, IAME, Rexon, LKE, Vortex, and TM:^[28]

More information Applicant, Brand ...

Applicant	Brand	Model	Homolog No
ASPA Srl	Modena Engines	ME-K	032-EN-17
IAME SpA SU	IAME	Reedster 5	040-EN-66
Karlheinz Hahn	Rexon Motors	Primaballerina	035-EN-17
Lenzokart Srl	LKE	LK2	033-EN-20
OTK Kart Group Srl	Vortex	VTS	012-EN-11
TM Racing SpA	TM Kart	S3-Senior	041-EN-03

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By year