This class is the open 125cc gearbox class. It is open to the use of motor-cross two stroke engines but by far the popular choice are the grand prix engines supplied by Honda (rs125) & Yamaha (tz125). In this class you are allowed the use of full body kits & wings etc.
Front & rear brakes are compulsory. Although not compulsory, leather race suits are highly recommended.
To be successful in this class a competitor must be prepared to get his or her hands dirty as these grand prix engines require regular maintenance & tuning to make good use of up to 50 odd horse power they are able to produce.
Running costs are reasonable. It could be said that due to the fact that these engines have only one cylinder that they cost half as much as a twin cylinder 250cc international Superkart to run i.e….1 piston & ring, one crankshaft, one set of reed petals etc.
The class weight for a 125cc gearbox Superkart is set at 180 kg minimum (kart & driver). Some quite impressive lap times can be achieved in this class…Phillip Island (1:42.7) Sydney motorsport park (1:37.3) on the GP circuit. Wakefield Park (1:01.7) On the shorter circuits times are only 2 to 3 seconds off the best lap times of the 250cc International Karts.
To get into this class used karts can be purchased from as cheap as $4000 to $5000. A new 125cc Superkart can vary in price from $20,000 upwards depending on your choice of engine, brakes, bodywork, instruments & so on.
Since the inception of the CAMS Australian Superkart Championship, in the 125cc Gearbox Class, nothing has taken a championship away from the Honda Rs125 grand prix engine.