Most 50cc mopeds can go about 40 miles per hour top speed on a flat surface. Although this is fast enough for some riders, many more desire their bike to travel faster. If you own a Speedfight 2 moped and wish it had a little bit more "oomph" to it, there are upgrades you can perform. The removal of your air filter, removal of the exhaust restrictor and replacement of the variator rollers can all increase performance, top speed and acceleration.
Remove the air filter cover of your Speedfight using your screwdriver. The air filter cover controls how much air flow the engine gets; often this cover simply restricts the top speed of your bike. The cover is held on by one screw, and is located directly above the carburettor of your Speedfight.
Push a long-necked, thin chisel into the end of your exhaust pipe. Keep pushing up the pipe until you feel it hit something. This is the exhaust restrictor, which restricts the air flow out of the exhaust, slowing the bike down. Using a hammer, gently tap the chisel until you hear this restrictor break. The next time you start your moped, it will come out of the back of the exhaust.
Locate the ignition cover, which is located on the right side of the Speedfight, and is held in-place with 3 to 6 bolts. Remove this cover using a wrench to expose the variator and the clutch system.
Remove the single bolt holding the variator in place. Pull this bolt out, and remove the variator itself. Six plastic "rollers" will fall out. These are little, plastic rollers that control acceleration. Replace these with modified rollers, which can be purchased online or direct from Peugeot. Put the modified rollers into the variator, and replace the variator and the ignition cover.
Start up the Speedfight, and give it a test ride to make sure all of the upgrades and modifications work correctly.
If you are uncomfortable working on your moped, do not try adding upgrades to it. Take it into a repair shop so the mechanics can upgrade it as you deem necessary.