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 2020 book

Note this amendment to Kart Licencing issued Dec 2019 for 2020

Guidance Sheet for the new bumper regulations

The regulations for the core classes are found in the Karting UK Yearbook. Click here for a copy of the 2020 Karting Yearbook (known as the Gold Book)

Go to the bottom of the page for the class structure and diagrams

Amendments to the 2020 Karting Yearbook

Amendment No 1 for the 2020 Kart Yearbook (Senior X30 class weight is 162kg)

Amendments to the 2019 MSA Kart Race Yearbook will be published here:

Amendment No 1 relating to number plates for Rotax Master 2019

Amendment 2 is relating to Ram Air in gearbox is re-issued 1.2.19

Honda Tech Regs V15a for 2020 – note these supersede V15 from 1.4.2020
This version includes the clarifications issued on 8 Jan, adds a new tool for magnet and piston and one or two other clarifications.  The details on the allowance to comply with either V14A or V15 words are removed.

Amendment No 1 for the Honda Tech Regs V15a for 2020 issued 1 May 2020

2020  Honda GX160 Tech Regs V15 is here, engines complying with V14A or V15 will be eligible until 31 March.  V15 amendments include only one clutch type, one emulsion tube and one oil and a catch tank for the engine breather pipe, but do read them thoroughly.  Note the later photo of the catch tank in this version.

Note this clarification to the Honda V15 regulations issued 8.1.2020 to download
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)

Amendment 3 to permit Shell M in IAME Cadet & X30

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

Junior Gearbox (2019 version)

210 National (2020 Version)

450 4-stroke Gearbox (2019 version)

Gillard Junior Tyro (2018 awaited)

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 Clubman, and approved variations for Honda Senior, World Formula and Junior Clubman with one Honda engine.

Formula Libre, and the approved variation for

Junior Libre with two Honda engines

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 2020 (Download 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 130 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 175 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: