Start the reworking of the engine by removing the plugs installed by the manufacturer. For the Japanese technology for a start replace the switch - there is the main plug of the most common models. Replacement switch for tuning will remove the restriction on the maximum engine speed that will definitely give boost to maximum speed. Be sure to check the engine for wear of the crankshaft bearings and cylinder-piston, before installing the switch. The new models (made after 2000) often contain plugs in the muffler (catalysts and "whistles") and the variator (washers).
Replace the silencer of the resonance pipe that is compatible with your Chu, adjust the transmission.
Install the carburetor with the increased diameter of the diffuser. Easy to install and configure are carbs with a diameter of 17.5 mm. Replacing the carburetor, be sure to replace the air filter. There may come a sport filter of zero resistance.
Install a sports variator. The belt variator is also best to replace the amplified.
Install Chu Sport-class – is perhaps the most radical and effective way to increase capacity. At the same time pay attention to the bearings and crankshaft were in perfect condition, otherwise the increased load will destroy them very quickly.
Replace the exhaust system on the sport, the so-called "saxophone", which consists of a resonator, the exhaust manifold and the muffler). Well-chosen saxophone will increase capacity by 10-15% and allow to raise the maximum speed.
Better not leave the regular brake. Install disc brakes with hydraulic motors, use reinforced brake hoses, replace brake pads on a sport.