Pushing a two-stroke scooter to go faster involves a number of modifications. Some of the changes are minor and easy to do, and some changes produce significant differences.
Minor speed boosts
Buy a higher compression cylinder cap. Use the socket spanner and sockets to remove your old stock cylinder cap. Remove the barrel and install a new cylinder gasket. Reinstall the stock barrel, greasing the inside with engine oil to allow the piston to slide back in as the barrel sits on the cylinder studs. Push it down onto the engine until the cylinder seats properly. Install the performance cylinder and screw on the nuts. Tighten them down in a diagonal pattern to avoid warping the new cylinder head and to factory specification. Change out the fuel to use a higher octane petrol (97 octane or more, i.e., racing fuel).
Replace the stock exhaust with a performance pipe. Use crescent spanners and a socket spanner to loosen the old exhaust's securing nuts and screws. Pop it off with a rubber mallet. Install the new performance pipe, attaching it to the same exhaust pipe exiting the cylinder. Use larger carburettor jets to provide more fuel to the engine for the performance pipe and cylinder head temperature increase.
Remove all scooter body accessories and spare wheel to reduce weight. Use a crescent spanner and socket set as needed to detach various items. Change the scooter seat to a performance seat if possible. Use a socket set to loosen and remove the old seat. Obtain a smaller, flatter simple pad seat to reduce weight. Either bolt or screw it onto the frame where you would normally sit.
Increase traction and rebound by using performance shocks and larger tyres. Unbolt the old shocks from the front and back of the scooter with a crescent spanner and socket set. Place the new shock in the same position and bolt it in. Take off the stock tyres by removing the wheels, deflating them, removing the old tyres and inner tubes and replacing them with 10 cm (4 inch) tyres and tubes. Reinflate and bolt the wheels back onto the wheel hubs.
Major speed increases
Using socket spanners, screwdrivers and other workshop tools as needed, remove the scooter engine from the scooter. Perform a complete tear down of the engine, removing all parts. Clean the engine parts and casings using a solvent to break up grease and oil.
Using a grinding tool, grind out the intake and cylinder ports so that they match the larger performance carburettor and performance cylinder you plan to use. Use the gaskets as a grinding template if one is not available. Remove any shavings. Clean the engine casings once more. Rebuild the engine using new gaskets, seals and bearings. Reinstall the rebuilt engine into the scooter with the performance cylinder installed.
Attach the new carburettor and hook up all electrical and fuel lines. Install a new performance pipe for the exhaust as well. Test the engine by starting it and letting it idle. Make carburettor adjustments to idle speed and fuel/air mixture until the engine idles at a constant speed without throttle. Perform spark plug tests at different scooter engine speeds. Look for a chocolate brown colour on the spark plug tip. Adjust the carburettor jets for more fuel if the tip is white. Adjust jets for less fuel if the tip is oily black.
It's a good idea to install first-time performance parts with an experienced scooter mechanic who can guide you through the steps.
Many scooter warranties become voided with the addition of performance parts to a scooter.
Things you need
- Socket spanner and sockets
- Crescent spanner
- New engine gaskets
- New carburettor gaskets
- Rubber mallet
- Performance modified cylinder cap
- Performance cylinder barrel
- Performance exhaust
- Performance carburettor
- Performance suspension springs
- Performance seat
- 10 cm (4 inch) width scooter tyres