Streetstock 125cc


Engine capacity
The maximum allowed cubic capacity of the engine is 125 cc for naturally aspirated
Only manual transmission systems are permitted with a minimum of three gears and a maximum of six.
Final drive must be chain driven.
Engine type
Only four stroke engines are permitted.
The engine must be from a homologated road legal bike.
Explicitly No Motorcross, Mini moto, or GP competition engines
Air filter may be changed or removed.
Original Fuel Injection/Carb must remain standard diameter.
Jets size maybe changed on Carburettors and Fuel mapping devices (power commanders) to alter Fuelling on injectors may also fitted
Exhaust maybe modified or replaced
Engine Tuning
The engine must remain standard with no modification to the standard piston, valves, rods, crank, and cam-shaft.
Inlet and outlet may have any restrictions removed if they exist
If the engines were originally fitted with a Starter motor. The Starter must remain and be functional No modification to the timing of the engines ignition is allowed.
Cutting of the ignition or fuelling for the purpose of moving through the engines gears is allowed by either a quickshifter, mechanism or button system to the handle bar
The Frame, sub frame, must be a homologated road legal bike. Modifications such as extra brackets or cutting of the
sub frame are permitted. No other modification will be permitted.
Frame and swinging arm must match the engines make and model.
Explicitly No Motorcross, Mini moto, or GP competition frames
The forks must match the chassis and externally must remain un-changed.
Internal modifications are allowed.
Rear shocks will be allowed to be modified with no restrictions as long as it fits the original linkage for the swinging arm.
Must have been sold with the same make and model of bike which the chassis is. Permitted wheel diameters are 16” 17” 18”
Pads, lines, master cylinder, discs, and fluid are allowed to be changed for race products. Callipers must remain from the same make and model as the chassis. Disc’s must remain the same diameter as standard for the model of bike.
Brakes must comply with the ACU regulations
treaded and slick tyres and wets are permitted. Tyre warmers are also allowed. Slick tyres are restricted by the ACU age and license restrictions
Aftermarket fibreglass bodywork is permitted different styles are permitted
Standard road bodywork is permitted but must have mirrors removed. All lights, indicators must either be taped or removed. If rear light is to be used as a rain light it must have the brake switch disconnected.
If the bike original had no fairing it will be permitted with no fairing but must have number boards fitted a per the ACU rules.

All bikes must run a front mudguard