How to Re-Jet a Moped
- 1). Move the moped into a clear working area with good light. Shut off the fuel valve from the gas tank. Use a screwdriver to untie the existing banjo bolt on the fuel line connecting it to the carburetor. Disconnect the fuel line. Use crescent wrenches to disconnect the outward manifold of the carburetor from the engine.
- 2). Use flat head and Phillips screwdrivers to disassemble the carburetor. Use crescent wrenches where necessary to loosen various components. Place all the removed parts into a pan or bin for safekeeping. Remove all the old carburetor gaskets exposed and throw them away.
- 3). Wash out the carburetor frame and parts with carb cleaner. Unscrew the jets from the carburetor frame with a flat head screwdriver. Use a shop cloth to hold the jet assembly while carefully loosening the jet itself from the jet assembly. Write down the number printed on the side of the jet.
- 4). Replace the removed jet with a larger-numbered jet for more fuel and a smaller-numbered jet for less fuel delivery. Push the jet back into the assembly by hand. Place the assembly back into the carburetor and screw it into place with the flat head screwdriver. Do not over-tighten.
- 5). Rebuild the carburetor assembly with new gaskets, securing the parts either with screwdrivers or crescent wrenches, depending on the bolts and screws applied. Take the reassembled carburetor and reinstall it onto the engine intake manifold where it was previously removed. Bolt the carburetor back onto the engine with a crescent wrench.
- 6). Reattach the fuel line and use a screwdriver to secure it with a new banjo bolt clamp. Remove all the tools, and roll the moped out to the street.
- 7). Start the engine and let it run for 10 minutes. Stop the moped and use a socket wrench to pull out the spark plug. Check to see if it is chocolate brown on the tip. Ride the scooter around at speed and do the same spark plug test. If black and oily, redo the jetting with a smaller-numbered jet. If white, use a jet with a bigger number.
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