The main regulations for all motorsport in the UK is found in the Motorsport UK Yearbook, including the Kart Section U. There are important sections for licencing, judicial and safety which apply to kart racing. Click here for the whole 2021 book
The regulations for the core classes are found in the Karting UK Yearbook. Click here for a copy of the 2021 Karting Yearbook (known as the Gold Book)
Note this clarification issued on 27.6.19:
An updated, more environmentally-compliant Honda T2 engine is now in circulation with engine preparers and will shortly be seen at circuits. The external method of identifying this engine is that the engine number will start with a “4”. The only other obvious identifying factor is that the flywheel magnet might well be mounted in a green coloured holder. Scrutineering in all aspects will remain the same as current practice and it is not anticipated that this updated engine will require any regulation changes.
Please be aware that this engine will not be eligible for the Motorsport UK Honda National Championship during 2019. A notice to that effect will be issued as a bulletin to all competitors in that series.
Also note this clarification issued 4.5.18 for the Honda Tech Regs V13:
The following clarification is to be read in conjunction with paragraph 9 of the current Honda GX160 Technical Regulations v13a, and will be incorporated into the next update of these regulations:
“No spark plug electrode gap is specified in the regulations, and therefore the gap measurement is free. However, under the definition of “the standard, unmodified component” the electrode should still conform in shape and relative position to an original, boxed item by way of comparison.”
2018 Amendments for reference (should now be incorporated into the 2019 regs)
The KG Cadet rear plastic bumper is now approved for use, see here.
Smaller or new classes, or variations to the major classes, will have their own set of regulations, usually by way of a KTE (Kart Technical Exemption).
Here are some of the popular 2018 KTE’s, 2019 will be published when approved
210 National (2021 Version)
Clubs can also offer the Clubman classes (which are lower powered and do not need the driver to take the ARKS Test so Clubman licence is required and can be taken out on the day of the race if necessary) or Libre classes (which do need the ARKS Test). Between them they cater for engines which are no longer homologated with their own class structure, or clubs wishing to combine a class with several compatible engines or use an engine that may not be in the regular homologated class approvals. Motorsport UK / Karting UK is open to new approvals for Clubman or Libre.
Formula Libre, and the approved variation for
All of the above regulations can be found on the Motorsport UK Website
2016 Honda Technical Regulations V11a (MSA approved 23.5.16 for immediate implementation for the clarifications listed) and this version is needed for those with T1 engines.
International Regulations and lists of homologated equipment, including racewear, can be found on the CIK Website
Homologations are a method of certifying certain equipment, and are usually valid for a certain number of years, with regular dates (often every three years) for new applications. This method means that the sport has stability as equipment cannot be updated at a whim by the suppliers. The fiche is the technical document describing the equipment in often great detail. Competitors should have copies of the homologations and fiche for the equipment they are using.
Club regulations (supplementary regulations or championships regulations) must be approved by the MSA and must reference which classes are being offered and where the regulations for these classes can be found. Clubs usually put their local regulations on their website, see club listing. The championship regulations will also show how points and penalties are calculated.
Summary of Main Kart Classes for 2021 – see the 2021 Gold Book last page for the class table
|Number Plate/No.||Weight kg (with driver)
|Ages||Tyres – Dry||Tyres – Wet||Comments|
|Bambino||White/Black||69 or 71 if racing||6-8||Le Cont MSA04||Le Cont MSA04||Comer C50 MSA homologated 2-stroke engine|
|IAME Cadet||Yellow/Black||103||8-12||Dunlop SL3 MSUK||KT3 Barcoded||60cc Parilla Gazelle un-sealed engine, clutch, pull starter|
|Honda Cadet||Yellow/Red||103||8-12||Dunlop SL3 MSUK||KT3 Barcoded||GX160 4-stroke budget engine, clutch, pull starter|
|Junior TKM 2S||Blue/White||From 123||11#-16||Maxxis TKM Green||F TKM||As TKM with restrictor, optional clutch, optional TAG|
|MiniMax||Yellow/Black||130||11-14||Mojo D2XX CIK||Mojo W5 CIK||Restricted version of Rotax Junior Max|
|Junior Max||Red/White||148||13-16||Mojo D2XX CIK||Mojo W5 CIK||Junior version of Rotax Senior Max|
|MiniX||White/Black||132||11-14||Komet K1H||Komet K1W||Restricted version of X30 Junior|
|X30 Junior||Green/White||148||13-16||Komet K1H||Komet K1W||Junior version of X30 with restrictor|
|OK Junior||Yellow/Black||142||12-16||TBA||TBA||Junior version of OK, these are push start karts, not currently raced in UK|
|TKM 2S Extreme||Red/White||From 132||16#||Maxxis TKM Green||F TKM||115cc BT82, optional clutch, optional TAG|
|Rotax Max||Blue/White||162||16#||Mojo D5 CIK||Mojo W5 CIK||125cc d/drive commercial TAG class (electric start)|
|Rotax Max/177||Green/White||177||16#||Mojo D5 CIK||Mojo W5 CIK||Heavy-w’t version with 83kg min driver weight|
|X30 Senior||Yellow/Black||162||16#||Komet K2H||Komet K1W||Commercial TAG 125cc IAME engine, not sealed|
|OK Senior||Yellow/Black||152||16||TBA /TBA||TBA / TBA||International, not raced in UK|
|Formula Libre & Clubman||Various||16#||Various||Various||Catering for economy or minority classes such as Honda Junior and Senior, World Formula and older engines|
|KZ2||Yellow/Black||180||16||Le Cont SVC CIK||Le Cont SV1 CIK||International & British Championship 125cc gearbox class|
|KZ UK||Green/White||180||16||Le Cont SVC CIK||Le Cont SV1 CIK||125cc reed valve 6 gears with 30mm carburettor|
|250 National||White/Black||195/200*||16+||Dunlop,Vega all CIKOption||Same makes as Dry||Motocross 250cc single cylinder engines, 450 4-stroke and 175 IAME 2-stroke options, 125 Open may race in this class|
Key: + means 17 years minimum for long circuit racing. 2S: 2-stroke engine; 4S: 4-stroke engine (Classes are 2S unless otherwise shown)
# means year of the birthday with a National licence.
Many class regulations call for specific tyre markings on the tyres e.g. ABKC, JAG, MSA, MS UK, GB etc, See Kart Race Yearbook.
Junior classes have a minimum driver weight, for safety reasons. Junior TKM 37kg & MiniX, MiniMax 37, Junior Max, 42.5, and seniors for under 16’s.
Junior Max & Junior X30 may race in year of 13th birthday for experienced drivers
*250/210 Gearbox has two weights, one when short circuit or no bodywork is fitted, the heavier for when wings or long circuit bodywork is fitted.
Here are a couple of handy images demonstrating the class age ranges and possible driver weight range: