Regs
GX-UK Prokarts
2025 Technical Regulations
Introduction: - GX-UK Prokarts is a race series built around the GX200 engine and a wide variety of Prokart chassis’ in order to create a low-cost way to enter owner karting.
The class ethos is to allow all competitors to race competitively with longer life 4 stroke engines, stable class regulations and on a minimal budget.
Whilst the spirit of competitive racing is being embraced, certain concessions to more broadly used regulations have been implemented with the sole aim of reducing costs, whilst also opening up the class to as many competitors as possible.
The Series Organisers reserve the right to amend the regulations based on safety at short notice.
Minor clarifications to the regulations can be made with 4 weeks’ notice from affect and will be
published on the GX-UK and Modified Sprint Championship Facebook page and the Access Karting website (www.accesskarting-uk.com).
Any major rule changes such as, tyres, significant weight limit and chassis will only be done in
between a championship finishing and the next commencing unless subject to force majeure, to be called by the series organisers.
The GX-UK classes runs within the sporting regulations utilised by Access Karting, an IKR host. This will be made clear before each meeting.
In any scenarios when the GX-UK regulations are, or could be viewed as ambiguous the MSUK Honda cadet engine fische shall override, minus the restrictor rules.
A2. Engine
A2.1 All engines are to meet the standard sealed RPM spec or to the MSUK spec fiche. Replacement engine parts that are like for like and must be original Honda manufactured. Front Sprocket sizes open and does NOT have to be a Honda original part. There will however be a rev limit of 6500 as per previous Mod160 Clubman rules and organisers can ask to see a drivers readouts and have them amend their gearing accordingly. Organisers also retain the right to impose fixed gearing along the same lines as BPEC, tba. In reality GX motors are only making noise above 62/300 and so you gain nothing apart from unreliability revving higher.
A2.2 all engines are to run a clutched with a pull cord starting mechanism.
A2.3 engines are to be of the original stamped cc volume, 200cc only.
A2.4 fuel tanks must be mounted placed around the steering column in the more conventional karting layout, top tanks are not allowed.
A2.5 Maximum of 3 engines per entrant to be signed on per race day, these serial numbers must be submitted in advance of them being raced by any competitor. Force majeure can be called by speaking with and gaining approval from the series organiser.
A2.6 Competitors engines must meet one of the following sealing standards for 200cc engines
200cc unrestricted – RPM red seals or the Access Karting Yellow seal via Monkey Motorsport/PKE
A2.7 Each competitor will be allocated a maximum of 6 seals per season, these can be allocated over a single engine or up to 4 engines as is the preference of the entrant. The only instance that more than 6 seals will be allocated is if the competitor can demonstrate material damage to the engine to an official of Access Karting. (numbers of both the RPM seals or Access Karting seals will be tracked by the series)
A2.8 Engine mount may be aluminium, steel or magnesium
A2.9 No taping of fans unless in a situation where the CoC has declared the meeting ‘open’ or ‘wet’
A3. Airfilter and box
A3.1. Airboxes and filters must conform to the standard shape and position as they are when sold and cannot be modified.
A3.3a. No drilling of the airbox or filter is permitted with the exception of fitting a bracket for the oil overflow catch bottle, these cannot then be left exposed if the bottle is removed.
A3.4b Air Filter must be intact with all the relevant elements present as per the MSUK Honda Cadet fische
A4. Carburettors
A4.1 The only permitted carburettor is the standard Honda carburettor as supplied as standard as per the fisch.
A4.2 All 200cc carbs will utilise the W50 or 922 emulsion tube and may only be use a 75 jet at all times.
A5 Exhaust
A5.1 All 4 different configurations of the GX160/200 exhausts are permitted. These are identified as the original black square box exhaust as sold when standard, the DEP1 cadet exhaust, the oval exhaust and the circular exhaust as sold by RPM.
A5.2 The oval and circular style exhausts must run the heat shield they are supplied with as standard as a safety feature provided the brackets on the exhaust are present, these cant be removed if sold as standard.
A6 Chassis
A6.1 Permitted Chassis
1) Any recognised Prokart permitted, it is advisable to seek chassis acceptance prior to attempting to race with it.
a) 2, 3, 4 or 5 Bearing
b) Adjustable rear ride height is permitted
A6.2 A maximum of 2 removable seat stays is permitted alongside a rear U mount if required. These can be fitted in any configuration.
A6.3 Axles up to a maximum diameter of 30mm are permitted. Hollow or solid axles are permitted
A6.4 Extended rear hubs are permitted, hubs may overhang the rear axle.
A6.6 Akerman or single fixing point columns can be used.
A7 Chainguards/Fingerguards
A7.1 Fully enclosed chain guard must be fitted to enclose front engine sprocket and rear sprocket.
This can be modified to fit provided the chain remains enclosed. No chain must be visible when looking from above the chainguard, or if you look across from the non engine side of the axle along the axle line.
A8 Brakes
A8.1 Brakes can be hydraulic, or cable operated
A8.2 Calliper and Master Cylinder are free, except for
1) Brake disc must be steel, solid or vented, cross drilled is permitted, floating discs are also allowed.
2) No ABS
3) Maximum of 1 pad per side and 2 pistons per pad.
4) Self-adjusting systems are allowed
A8.3 Brakes must operate on the rear wheels only.
A8.4 Secondary (back-up) brake cable is required between pedal and master cylinder.
A9 Wheels and Tyres
A9.1 Aluminium or Magnesium wheels are permitted but must be of one piece moulding
A9.2 Front wheels are to be bearing or front hubs three stud types.
A9.3 Stub axles are open provided they don’t house a front braking system
A9.4 Maximum wheel width is 122mm front and 212mm rear, measured internally between the
beads. Maximum outer width is 131mm and 222mm respectively.
A9.5 Tyres are to be Maxxis Sports only two set must be used for the whole season, numbers to be lodged with organisers. The wet tyre is the Maxxi SL1W, two sets per meeting can be signed on
A9.5b tyres may only be replaced or changed outside of allocation on safety grounds after inspection and agreement.
A9.5c Treatment of tyres is not permitted, no chemicals can be added to the tyres and durometer
tests will be carried out against the base mark of the tyre.
A10 Maximum Width/Track
A10.1 Maximum front track, measured from outer most points of front tyres/wheels – 1200mm
A10.2 Maximum rear track, measured from outer most points of rear tyres/wheels – 1400mm
A11 Exotic materials
A11.1 Magnesium is allowed except for where specified within the regulations
A11.2 Carbon Fibre/Carbon composites are allowed except where specified in the regulations
A11.3 Titanium is allowed except for where specified within the regulations
A11.4 No other form of exotic material are permitted including but not limited to titanium etc
A12 Bodywork
A12.1 Chassis must run side pods and front bumper/nose cone – style Unico crash tested or newer
A12.2 Competitors must run all sponsor and Access Karting stickers supplier on either their Nassau panel, side pods, engine cover or helmets or helmet where required.
A13 Minimum Weights
GX-UK Prokart – GX200 unrestricted 182kg
A Heavies class may be introduced subject to numbers, weight TBA but liable to be 200
A14 Number Plates/Board
A14.1 SENIOR;- Race numbers are to be red on a white background. Numbers to be displayed front, rear and sides.
A15 Rear Bumpers
A15.1 Full length rear bumper covering at least 50% of the rear tyres. The rear bumper CANNOT
protrude beyond the outer edge of the rear wheels, plastic or metal secured in line with normal Prokart standards.
A16 Rev Counters / Data Loggers
A16.1 Rev Counters are mandatory to ensure max revs are not exceeded and GPS systems are allowed such as the Mychron and Alfano
A17 Steering Wheels
A17.1 Steering wheels are open fitting type, 3 and 6 bolt are allowed
A17.2 Flat top or/and bottom permitted
A17.3 3 spoke shaped fitment area for data logger wheels are allowed
A18 Age ranges
A18.1 A competitor can elect to compete as a senior at 15 provided they are 16 in that calendar year
A18.2 Once a competitor has taken part in a senior race, they cannot revert to being a junior under any circumstances.