Streetstock 125

Engine capacity
Maximum 125cc/Minimum 120cc OE engine

The use of superchargers/turbochargers is prohibited

Engine type
Only four stroke OE homologated road engines.
No competition engines

Air filter and box may be changed or removed.
Original OE Fuel Injection to remain as fitted from manufacturer

All air-cooled engines have “NO” carb size restrictions

Only OE supplied ECU/CDI permitted (Euro/USA/UK all models ECU/CDI permitted) NO altered or race ECU/CDI

Any carb “UPTO” standard OE diameter permitted on water-cooled carb engines

Jets/needles/tubes may be changed  on carburettors

Fuel mapping plug in boxes eg. power commanders/resistors/ignition boxes  can be fitted but standard OE ECU/CDI must still be used

Exhaust maybe modified or replaced

Engine Tuning not permitted and must remain OE standard with no internal modifications at all
Starter motors if originally fitted must remain and be functional

No modification to the timing of the engines ignition pick-up or flywheel allowed.
Cutting of the ignition/fueling for the purpose of changing gears is allowed by a quickshifter mechanism

Seat subframe may be modified/changed
No home made or one off or competition frames

The forks must remain standard OE, any internal modifications are allowed , external preload adjusters allowed.

You can use “ANY” forks fitted to the same make/model of bike irrespective of year eg YZF-125 any year YZF-r125 forks/wheels, CBR125 any year forks/wheels “BUT” all parts must be originally fitted from the same Manufacturer 

Rear shocks can be modified/replaced with no restrictions as long as they fit the original mounting points


*Remain OE fitment for manufacturer permitted size 16″ 17″ 18″

Pads, lines, master cylinders, discs, and footrest/hangers are allowed to be changed. Disc’s must remain the OE diameter for the model of bike.

Any chain and sprocket size can be used

Any tyres permitted, tyre warmers are also allowed.

Any aftermarket fibreglass bodywork is permitted
Standard road bodywork is permitted but must have mirrors/stands removed. Head lamp and rear light glasses must be adequately taped to prevent splintering. Unused wiring for lights and switches etc may be removed.

Replacement parts only OE or pattern to OE spec parts can be used in engines

The only liquid engine coolant permitted is water

Oil sump plug and filler plug must be lock wired

A red rain light fitted to the rear of the Motorcycle


Max 125cc/Minimum 120cc fourstroke engine no tuning restrictions

The use of superchargers/turbochargers is prohibited


Any chassis may be used

The only Permitted wheel diameters are 16” 17” 18”

Any tyres are permitted as are tyre warmers

Any race bodywork can be fitted.

The only liquid engine coolant permitted is water

Oil sump plug and filler plug must be lock wired

A red rain light must be fitted to the rear of the motorcycle


Max 50cc two-stroke, no tuning restrictions

* Permitted wheel diameters are 16” 17” 18”

Any race bodywork can be fitted.

The use of superchargers/turbochargers is prohibited

The only liquid engine coolant permitted is water

Oil sump plug and filler plug must be lock wired

A red rain light must be fitted to the rear of the motorcycle

Anything “NOT” mentioned above must be approved by the club

Minimum age 16 *dispensation may be given if previous race experience is proven*

Riders per team 2-6 mandatory rider change every 30 minutes +5 minute window

Newcomers are advised to wear hi-vis bibs


  • The Technical Officer shall check the machine for class compliance.
  • Noise limit Max 99dB(A), The noise test will be conducted with the microphone placed at 50cm from the exhaust pipe at an angle of 45°
    measured from the centre-line of the exhaust end and at the height of the exhaust pipe, but at least 20cm above the ground.
    upto 250cc single (4-stroke) 5,500rpm
    upto 125 single (2-stroke) 7,000rpm
  • Exhaust system regs, Streetstock: minimum 320mm end can sold for the correct bike over the counter from a proven manufacturer named brand with db killer,no unamed/home built or copy cans

  • Moto4: A minimum 320mm end can with db killer fitted.

    50cc: 99dB(A) noise limit

    We suggest 400mm+ if you struggle with 320mm and 99dB(A)

    “ALL” bikes must be 99dB(A) or below,any bikes above will not be allowed to take part untill tested at 99dB(A) or below, this is to allow for noise increase during the race, If the can is damaged during the event it must be replaced or repaired to conform to the 99dB(A) rule.End cans must be repacked if they go above the 99dB(A) limit.
    approved manufacturers

    The noise limit at most circuits is measured at an average over 30 minutes, this is in addition to a maximum single bike noise limit also monitored by the circuit.The goal is to comfortably be below the average and to prevent any single bike breaking the individual noise limit during the event and preventing black flags during the race.Exhausts should be regularly repacked to ensure they remain below the maximum allowed 99dB(A) limit.

  • Tyres must be race compound Treaded,slick or wets
  • NUMBER PLATES One number must be displayed on the front of the motorcycle and  two side number plates. The numbers must be clearly visible to the public and marshals on
    both sides of the machine.

  • To be classed as a finisher you must complete either 50% of class leaders laps or pass the chequered flag at end of race

  • All riders MUST attend riders briefing for that days race. No briefing No racing
  • It is the responsibility of the rider to ensure that a machine used in competition is mechanically
    and structurally in a safe condition.
  • Oil sump plug and filler plug must be lock wired.
  • All motorcycles must have a functioning red light mounted at the rear of the machine to be used during rain or low visibility conditions (and front light when required) if your light isn’t working when needed you WILL be blacked flagged until a working light is fitted.
  • Throttle controls must be self-closing.
  • Petrol and oil filler caps when closed must be leak proof. They must be securely locked to prevent
    accidental opening.
    Catch bottles / tanks must be fitted to the gearbox breather pipe(unless standard breather goes into airbox), fuel tank breather pipe, carburettor overflow pipe(s) and the radiator overflow pipe (if applicable) , where an oil breather pipe is fitted the outlet must discharge into a catch tank located in an easily accessible position and which must be emptied before the start of the race.
  • All handlebar levers (clutch, brake, etc.) must be, in principle, ball ended or be rounded.
  • Minimum 2 riders per team, Le Mans start and rider 1 is the competitor to run across circuit,start the motorcycle and complete first lap, The person holding the bike must ONLY hold it for Rider 1 and not start the engine or push towards rider 1 across the circuit.
  • Only 1 bike per team for the race.
  • Teams may change ANY/ALL components on the motorcycle EXCEPT they MUST finish on the same frame as started, the only component not allowed to be substituted is the main frame.
  • Any exceptionally slow riders/bikes may be black flagged, Clerk of Course descretion.
  • Any Machine without electric/Kick starter that needs a push start will start from the back of the grid unless they have a paddock/roller starter then the rider can start in qualifying position using starter (which must be removed immediately)
  • Any infringement of the rules and regulations will be penalised with one of the following penalties:
    Disqualification – withdrawal of Championship points – suspension.
  • Quickfill/fuel dump containers are not permitted.
  • Max 10 liter Fuel cans.
  • All engines must be switched OFF in pitlane between the pre-designated areas on the day, usually but not confined to cones/Freetech arch at entry/exit to pitlane ANY bike running in this area will result in IMMEDIATE disqualification from the days event.
  • Only 1 person (rider or helper) may push the motorcycle through the pits
  • All machines must remain in designated parc ferme after the race for tech inspection, any motorcycle not in parc ferme or removed before permission will be excluded from the days results
  • Any motorcycles found to be oversize will result in a permanant ban from future events


NATIONAL FLAG or START LIGHTS :Signal for the Start of the Race.

Red: Race Stopped. IMMEDIATELY SLOW (with care) & proceed at touring pace to a stop
area as indicated. This will be pointed out at riders briefing or may be indicated by a circuit
Any infringement of this rule will be penalised with one of the following penalties:
Disqualification – withdrawal of Championship points – suspension.

Yellow (Stationary): Proceed with caution – slow down,no overtaking up until the point
where the green flag is shown. Riders not observing the caution or overtaking rule will be

Yellow (Waved): Extreme caution. Be prepared to stop – slow down, no overtaking up until
the point where the green flag is shown. Riders not observing the caution or overtaking rule
will be penalised.

Yellow: (With stripes): Caution, slippery surface – Ride accordingly.

Green: Safe to Race

Black: (with riders number shown) Mechanical / Riding Fault – Return to Pits and consult

Chequered: End of race Return to Paddock or Park Fermē

Any infringement of the flag rules during a practice session will result in the cancellation of
the time of the lap during which the infraction occurred.
In case of infringement of this rule during the race, a time penalty may be imposed. In both
cases, further penalties

Riders must not ride or push their motorcycles in the opposite direction of the circuit, either on
the track or in the pit lane


During practice and racing riders must wear the following clothing and footwear:
A complete all in one leather suit or a Suit that is zipped together at the waist are permitted.

Competitor’s helmets bearing the current ACU gold stamp in sound condition and properly
fitted must be worn. Overseas riders may use helmet as approved by their own FMN.

Competitor’s footwear must be of leather and a minimum
height of 200mm to provide, with the suit, complete protection. No areas of skin to be left
exposed between the leg of the suit and the top of the boot.

Competitors must wear leather protective gloves. No areas of skin to be left exposed between
the wrist of the suit and the wrist of the glove.

One machine number must be displayed on the front of the motorcycle.

All riders and press must sign a declaration on the relevant signing on form 

Terms & Conditions

Bookings for meetings

Cancellations of 7  days or more of the date of the event

Full refund less an administration cost of £20 per team

Cancellations of less than 7 days of the date of the event

No refund, no credit note.

Force Majeure

The Clerk of the Course has the right to alter, abandon, cancel or postpone all or any part of a meeting
for reasons of force majeure. Such a decision shall not be subject to any protest.

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