There are number of ways to improve the top speed of your motor scooter. One way is simply cleaning the engine. As you drive, dirt and deposits gradually build up in the engine, which makes it work harder and gradually lose efficiency. Cleaning the carburettor, engine parts and cylinder area with a solvent or engine degreaser wash can help increase performance, as can changing the oil and filters.
Check with your local government on the proper use of engine degreaser. Be sure you understand the rules regarding treatment use before you start cleaning.
Take off any removable body panels to gain access to the engine area. Wrap the air intake and electrical components with plastic bags or cling film to prevent water entry. Coat the engine parts with degreaser, but avoid all external electrical parts and the carburettor intake.
Let the degreaser soak in for a few minutes. Spray again in areas that are thick with grease and road grit. Use a plastic wire brush to gently break loose significant deposits. Once complete, use a water hose to pressure wash the engine. Again, avoid all electrical components and the carburettor.
Complete the washing and remove any remaining degreaser from the engine. Let the scooter air dry. Do not put the scooter in an enclosed structure while it is still giving off fumes. Degreaser contains solvents which release gas when drying and are flammable.
Remove the engine from the scooter after disconnecting all electrical connections, cables and fuel lines. Remove the rear tire and wheel. Remove the cylinder by unbolting it with a socket wrench and carefully slipping it off the piston. Dismantle all remaining parts with a crescent wrench and socket wrench. Unbolt all engine case nuts, take apart the engine cases, and remove all outside and inside engine parts. Remove old engine seals and bearings as well. Remove remnants of old gaskets by peeling them off the cases. Throw away the old bearings, oil seals and gasket remnants.
Take a small wood block and small hammer and place the wood on the inside of the cylinder surface. Tap the wood with the hammer hard enough to remove any hard carbon build-up. Do the same for the piston head. Continue this process until the engine is fairly clean. Use carburettor cleaner to break down stubborn areas. Use this same cleaner on the carburettor.
Bring all the engine parts outside. Wash the remaining engine parts thoroughly using a plastic wire brush and a solvent (i.e., kerosene or similar). Let the washed parts air dry at least 12 hours to allow any remaining solvent fumes to dissipate. Do not bring the solvent-wet parts into an enclosed area or near a flame source (a garage water heater for example).
Rebuild the engine by reversing the disassembly procedure. Use new engine case gaskets, oil seals and bearings in the rebuild. Re-install the completed engine back into the scooter and hook up all electrical connections, fuel lines and control cables. Add new oil and change all filters. Test the scooter to be sure it runs well and rides without problems. Once tested, push its limits a bit to enjoy the benefits of a cleaner engine.
Take your time cleaning and verify all deposits are removed properly.
Never have a flame source in the vicinity when using a degreaser or solvent on an engine. Use industrial rubber gloves when working with any kind of degreaser or solvent to prevent damage to bare skin.