50cc Pro Mini

Wheel size : must be 10" rear and 10" or 12" front. Engine - Must be maximum 50cc. No stroker cranks. Permitted engine mods include: Piston, Cylinder head porting, (must use stock Honda XR/CRF50 cylinder head), Exhaust, air filter,Camshaft, carburetor, racing ignitions,. Transmission: Must be 3 or 4 speed semi automatic, no manual clutches , close ratio transmissions, 3 speed or 4 speed,heavy duty clutch springs. Rolling chassis - Unlimited mods allowed - permitted mods include replacement forks, frame, swingarm, shock, wheels (10" rear and 10" or 12" front) brakes, gear shifter, footpegs, brake pedal, handlebars, throttle, seat, plastics, skid plate, tyres, chain and sprockets.

88cc Pro Mini

Wheel size : must be 10" rear and 10" or 12" front. Engine - Must be maximum 88cc using stock Honda stroke/crank and 52mm bore maximum. Any exhaust, cylinder head, camshaft, piston permitted. Any ignition. Transmission. Can use manual clutch, close ratio transmission. Rolling chassis - Unlimited mods allowed - permitted mods include replacement forks, frame, swingarm, shock, wheels (10" rear and 10" or 12" front) brakes, gear shifter, footpegs, brake pedal, handlebars, throttle, seat, plastics, skid plate, tyres, chain and sprockets.

Open Mini

Wheel size : must be 10" rear and 10" or 12" front. Engine - Must be maximum 160cc. Any cylinder head, camshaft, piston permitted. Any ignition. Transmission. Can use manual clutch, close ratio transmission. Rolling chassis - Unlimited mods allowed - permitted mods include replacement forks, frame, swingarm, shock, wheels (10" rear and 10" or 12" front) brakes, gear shifter, footpegs, brake pedal, handlebars, throttle, seat, plastics, skid plate, tyres, chain and sprockets.

Superstock Midsize

(This class is based around a Kawasaki KLX110) Wheel size : must be 12" rear and 12" or 14" front. Engine - Must be maximum 110cc. using stock Honda KLX cylinder head - no head modifications allowed. Replacement camshaft, air filter, jets, exhaust, permitted, Must use stock piston and cylinder - no stroker cranks. Carburetor must be stock except for jet change. Transmission - Must use stock Kawasaki semi auto clutch, heavy duty clutch springs permitted. Must use stock Kawasaki 3 or 4 speed transmission. Chain and sprockets permitted, Rolling chassis - must use stock KLX110 frame and swingarm - replacement rear shock absorber allowed. Forks - must use stock KLX110 forks sliders and fork legs- replacement springs and internal mods permitted. Wheels - Must use stock Kawasaki hubs, rim and spoke upgrades permitted. Can change Handle bars, Handlebar clamps, Throttle, cables, seat, plastics, footpegs and footpeg mount, gear shifter, brake pedal, skid plate, tyres.

Open Midsize

Wheel size : must be 12" rear and 12" or 14" front. Engine Must be maximum 160cc. Any cylinder head, camshaft, piston permitted. Any ignition. Transmission. Can use manual clutches and close ratio transmission. Rolling chassis - Unlimited mods allowed - permitted mods include replacement forks, frame, swingarm, shock, wheels,brakes, gear shifter, footpegs, brake pedal, handlebars, throttle, seat, plastics, skid plate, tyres, chain and sprockets.

Number plates

These regulations will have to be modified slightly from the "motocross" regulations as front number plates and side number plates are generally smaller on the mini and midsize bikes. Minimum size for the front number plate should be 200mm by 160mm.

Number plate background colours

Overview

Minibikes race in the MINI4GB are effectively two different sizes, "minibike" and "midsize". All minibikes must be 4 stroke with an open cradle style frame. The bikes are then divided into classes by wheel size, engine capacity and permitted modifications. Read below for our “at a glance” guide to working out which class you can race your

Minibike

A bike is classed as being a minibike when it uses a 10" rear wheel and a 10" or 12" front wheel. The cubic capacity of the engine then determines which "minibike" class it is raced in. The easy way to see if your bike is classed as a minibike, measure the diameter of the rim, not including the tyre. If its 10”, you have a “minibike”. The next important thing to know is the engine size, ifs 50cc, then you will race in 50cc Pro Mini class, if its 88cc, then its 88cc Pro Mini and finally, if its over 88cc, then it will be Open Minibike, there are a lot of bikes that fall into this class regardless of whether its 110cc, 125cc or 145cc, you can have up to 160cc in the Open Minibike class

Midsize

A bike is classed as being a midsize when it uses a 12" rear wheel and 12" or 14" front wheel. The cubic capacity of the engine then determines which "Midsize" class it is raced in. In the case of the "Superstock" classes, the only bike permitted to race is the Kawasaki KLX110 (with the eception of the 2005 Suzuki DRZ110, which was a Kawasaki in yellow for one year only). The Open Midsize class is for anybike with a 12” rear wheel, it can be any size of engine, the maximum permitted size is 160cc. Bikes in this class vary from 125cc through to 160cc.

Superstock

This classes have been formulated to encourage the use of good quality Japanese machinery, ensure a level playing field as far as machine modifications are concerned and to provide a reasonably priced entry into four stroke minibike racing. You can purchase a brand new, race ready Superstock Midsize from our series sponsor, Minibikepro for just over £2000. These bikes are super reliable and a great way to get started without having to spend a lot of money on tuning engines. Click this link

Machine suitability

As with all ACU sanctioned events, machinery must conform to a minimum level of safety regulations for both the rider and competitors safety. All bikes will be subject to ACU scruitineering practice as outline in the standing regulations and any bikes failing to satisfy the require regulations will not be deemed fit for competition.