Legally, a moped cannot exceed 30 or 35mph (depending on where you live). Yet some moped motors are capable of much higher speeds than regulations stipulate. That is why their manufacturers install restricting devices. Here's how to make a moped go faster.
Remove the air filter or the baffle in the air box.
Install an expansion chamber in the muffler, or simply buy a performance muffler to replace the original. To modify the original, remove the exhaust pipe. Remove the restrictors that may be located in the muffler, or drill holes in them. You will probably need to grind the bolts off to get to the narrow pipe inside and then file it out. Also cut off the small pipe that extends out the side but doesn't hook into anything. Crimp closed the opening that's left on the exhaust after you cut off the narrow pipe.
Check the transmission of your moped. Verify that it has the correct amount of fluid specified in the manual. Excessive or dirty fluid can slow your performance.
Change your oil and oil filter. Use high-quality synthetic oil.
Remove the transmission cover. Remove the nut on the variator assembly. Pull the variator assembly out and look for a washer between the two halves of the pulleys. Remove this restrictor washer, replace the variator assembly and replace the nut.
Replace the main jet in the carburettor with a larger one. You will need to remove the carburettor to do this, then take the top off. Keep track of all your screws and plug the gas line, or gas will leak out.
Increasing the speed of a moped could require it to be registered as a motorcycle. Removing your baffle may create excessive noise. Modifications can affect the life of your engine. Illegal speeds can result in fines, confiscation, loss of driving privileges and collisions.