To improve the speed of a moped, clean various parts, check and fix the compression, replace tires and tubes, tension the chain, true the wheels and replace and gap the spark plugs. These improvements can be easy or difficult depending on your experience with mopeds.Continue Reading
Clean the carburetor, all points if there are any, the exhaust pipe, port and the wheel bearings. Repack the wheel bearings after cleaning.
Check the compression, and compare it to the specifications in the QT50's manual. Low compression causes the moped to run poorly, resulting in a decrease in speed.
Worn tubes and tires cause the moped to slow down. Replacing them improves speed and makes the moped safer to ride.
If your chain is too tight, you lose speed. A chain that's too loose can fall off the sprocket. Your chain should have between 1/2 and 1 inch of up-and-down travel.
Make sure the wheels are true. This makes the ride smoother and safer. Truing can be difficult and also takes between four and six hours to complete, so you may want to hire a professional if you lack truing experience.
Replace spark plugs as needed, and be sure to gap them properly. Keep spare spark plugs on hand to replace as needed.