Regs
100-UK (Senior and Junior) 2025
Technical Regulations
A1. Introduction: - The 100-UK Is a race series built around the TKM BT82 (100cc) engine and simple chassis ethos to allow all competitors to race competitively with longer life 2 stroke engines, stable class regulations and on a sensible budget. Whilst the spirit of the early Tal-ko regulations are being embraced, certain changes have been implemented with the sole aim of reducing costs, whilst also opening up the class to as many competitors as possible without affecting performance and allowing majority of equipment to still be mainstream legal 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 100-UK Facebook Page and the Access Karting-UK website. 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.
A2. Engine
A2.1 All engines are to meet the Tal-Ko fiche and all internal components must be genuine Tal-Ko items including base gaskets and number to meet fiche. Except for the follow - Front Sprocket can be 9t, 10t or 11t but does NOT have to be TKM stamped - Fin rubbers are optional - 1 x Sealing head nut to be fitted to the engine to allow for engine sealing at an event. This can be fitted after or before a heat when requested by the scrutineer.
A2.2 Direct Drive engines or clutched engine with external starters are permitted – TAG variants are not allowed.
A2.3 Only cast liners are permitted – CNC Liners are prohibited.
A2.4 Motoplat (9600903-1) or PVL ignition (TKM Stamped version) are both permissible.
A2.4b Ignition timing as per Tal-Ko fiche being Motoplat 2.0mm to 3.0mm BTDC and PVL 1.5mm to 2.1mm BTDC A2.7 Minimum head volume is 11cc (measure by Burette) or 10.6cc (measured by Digital).
A2.8 Period head only – no EaziStart heads allowed
A2.9 TKM pistons only
A2.10 Maximum serial number of 6,799 on the crankcases to keep the period bottom end
A2.11 Maximum of 2 engines per entrant to be signed on per race day.
A2.12 Maximum of 4 engines to be used over the year for any single entrant (engines can be shared across multiple entrants such as pooled or hired engines)
A2.13 External repainting of barrel and head allow for aesthetics – outside only.
A2.14 Engine mount may be aluminium, steel or magnesium
A3. Airboxes
A3.1. Airboxes can be either of the TKM versions to maintain the period look or the RR ASR EVO 100 airbox which is the same as the ‘Mark 2” TKM system without the TKM badge. Socorem or other airboxes etc are not allowed. If in doubt seek clarification before attempting to race. See (Appendix N2)
A3.2. Where using 2 trumpets the maximum permitted internal diameter of 23mm applies.
A3.3a. No drilling of the airbox is permitted except for the following:
A3.3b On the original “Dome” TKM Airbox, a maximum of 3 holes expressly used for the sole purpose of securing the dome to the back plate. Where a hole is drilled it must be used.
A3.3c One small drill hole can be added to the fin on the underside of the new style airbox to allow for a fixing to be added for stability. This may not perforate the main element of the airbox, nor may it increase airflow to the filter on any way other than maintaining the orientation of the airbox.
A3.4 Internal Air Filter must be present – type free – of comparable filtration/restriction to original part.
A3.4b Air Filter must be intact.
A4. Carburettors
A4.1 The only permitted carburettor is the Walbro WB19 (TKM Stamped) – No Modification except for the following;
A4.2 Extensions are permitted to both the low and the high jets if required for ease of adjustment by the driver.
A4.3 Carb Spacer block may only be modified, by the means of a slot, to aid the fitment/removal of the throttle cable.
A4.4 Helicoil/Timesert repairs are permissible.
A4.5 Walbro repair kits D10-WB and K10-WB are permitted.
A4.6 JUNIOR – to run appropriate TKM stamped restrictor between carb and engine. NO modification permitted. Colours and weights as per A13
A5 Exhaust
A5.1 Only small bore straight exhausts are permitted with the TKM stamp ONLY.
A5.2 End can also referred to as ‘Baked Bean’ can must be fitted – type free
A5.3 Exhausts must be intact both internally and externally, and as sold by Talko.
A6 Chassis
A6.1 Permitted Chassis - Senior 1) Any chassis homologated for the TKM class up to and including the 2001 homologation (1994-2003) 2) Any British non-gearbox 2 bearing chassis manufactured between 1983 and 1994 (onus is on entrant to prove age if it is not easily recognised) that meets the ethos and spirit of the TKM chassis regulations.
Being :- a) British Chassis b) 2 Bearing c) No adjustable rear ride height d) No adjustable torsion bars e) No adjustable camber system, such as rose joint systems allowed It is advisable to seek chassis acceptance prior to attempting to race with it.
A6.1b Permitted Chassis - Junior 1) Any chassis permitted for 100-UK seniors is eligible for the junior class
A6.2 If fitted, camber/caster adjustment must be removed and neutral pins fitted
A6.3 A maximum of 2 seat stays is permitted – No more than 1 per side which must be attached but metal fixings if present
A6.4 Axles up to a maximum diameter of 30mm are permitted. 30mm hollow axles are permitted
A6.4b No torsion devices maybe fitted to the kart or rear axle including rear bumper (twin bar rear bumpers are permitted provided they don’t have a removable/adjustable bar).
A6.4c Extended rear hubs are permitted, hubs may over hang the rear axle providing that they are of a 2 bolt design (bolts must be set out in parallel or side by side as appose to securing the same circular fixing point, or in series).
A6.5 Any adjustable torsion bars must be removed.
A6.6 Single point steering must be used – NO ACKERMAN, ackerman columns can be used providing only central mounting is used
A7 Chainguards/Fingerguards
A7.1 Fully enclosed chain guard must be fitted to enclose front engine sprocket or full chain guard can be modified and used in conjunction with TKM engine mounted front sprocket guard
A8 Brakes
A8.1 Brakes can be hydraulic or cable operated
A8.2 Caliper and Master Cylinder (if applicable) are free, except for 1) Brake disc must be steel, solid or vented, cross drilled is permitted 2) No ABS 3) Maximum of 1 pad per side and 2 pistons per pad. 4) Self-adjusting systems are NOT allowed
A8.3 Brakes must operate on the rear wheels only.
A8.4 Secondary (back-up) brake cable or bar 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 type. Front hubs are not permitted.
A9.3 Maximum permitted stub axle size is 17mm
A9.4 Maximum wheel width is 122mm front and 210mm rear, measured internally between the beads. Maximum outer width is 131mm and 217mm respectively.
A9.5 Nominated tyres for both Senior and Junior are
Dry Tyres - Dunlop SL3
Wet Tyres are Maxxis SLW
A9.5b Treatment of tyres is not permitted, not chemicals can be added to the tyres and durometer tests will be carried out against the base mark of the tyre
A9.6A No more than one set of slick tyres per meeting. In the event of a puncture/damage, the damaged tyre must be presented to a scrutineer who can authorise its replacement.
A9.6b No more than two sets of slicks to be used for the championship round, these must have the laser etched DK serial number present to be registered at a race weekend. These can be used tyres when first presented by a competitor.
A9.6C No more than two sets of wets can be nominated for a meeting. The sets must have a minimum of 1mm of tread prior to the start of any race. Scrutineer can and will perform measurements on the grid to ensure safety. Both sets of tyres for the meeting in question must be nominated before heat 1.
A9.6D Guests joining the series during rounds 1, 2 or 3 may use a new set of tyres but these must do a minimum of 3 rounds before a 2nd new set can be introduced. Guests joining from round 5 onwards will be supplied with a used set by the series to ensure there is no advantage over the members of the series
Tyres can be excluded from further use in a race meeting if measure at under 1mm of tread at anytime after a heat.
A10 Maximum Width/Track
A10.1 Maximum front track, measured from outer most points of front tyres/wheels – 1150mm
A10.2 Maximum rear track, measured from outer most points of rear tyres/wheels – 1350mm
A11 Exotic materials
A11.1 Magnesium is not allowed except for where specified within the regulations
A11.2 Carbon Fibre/Carbon composites are not allowed except for seat and floor tray
A11.3 No other form of exotic material are permitted including but not limited to titanium etc
A12 Bodywork Junior/Senior
A12.1 chassis must run side pods and front bumper/nose cone – style upto and including CIK02 period
A13 Minimum Weights
100UK Senior – 152kg
Junior - Unrestricted - 148kg (driver minimum 67kg in kit)
Junior - Purple TKM Restrictor - 142kg (driver minimum 57kg in kit)
Junior - Blue TKM Restrictor – 135kg (driver minimum 47kg in kit)
Junior - Gold TKM Restrictor – 128kg (driver minimum 39kg in kit)
Junior - Black TKM Restrictor – 123kg (driver minimum 34kg in kit)
A14 Number Plates/Board
A14.1 SENIOR;- Race numbers are to be white on red background. Numbers to be displayed front, rear and sides.
A14.2 – JUNIOR;- Race numbers are to be white on blue 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. The bumper must be of metal construction and be visible akin to the TKM class and period.
A15.2 JUNIOR – 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. The bumper must be of metal construction and be visible akin to the TKM class and period.
A16 Rev Counters / Data Loggers
A16.1 Rev Counters are allowed. System such as the Mychron and Alfano are allowed providing that they are only logging lap time and engine revolutions.
A17 Steering Wheels
A17.1 Steering wheels to be 3 bolt fitting type only
A17.2 Flat top and/or bottom permitted
A17.3 3 spoke without shaped fitment area for data logger