The 1981 Honda Express moped is part of the NC50 series of Honda mopeds. The 1981 Express offered an automatic choke, CD ignition and a direct kick starter for the first time in the series. Owners still had to stick to a regular maintenance schedule to keep their Honda Express running well, and many of the 1981 Express mopeds are still on the road today. Change the transmission oil on your 1981 Honda Express moped on a regular basis to keep it in great condition.
Park your Honda Express on a level and solid surface, and make sure the kickstand is supported on firm ground.
Place a drain pan under the transmission drain bolt. The drain bolt is located on the bottom of the transmission near the rear wheel on the left side of the moped (opposite the muffler, on the cover with Honda written on it).
Loosen the drain bolt with a 10-mm box wrench and let the oil drain out into the pan. When no more oil is draining, replace the bolt.
Remove the oil fill bolt with a 14-mm box wrench. (It is located on the face of the rear transmission casing, slightly below centre. The casing covers the axle of the rear wheel on the left side.)
Bend the flexible hose end of your funnel so the hose can be inserted into the bolt hole and the funnel part will remain upright. Pour 900cc of 10w30 oil into the funnel. Your transmission may take slightly more or less depending on how well you drained the old oil out. When oil begins to run out of the hole around the funnel end the transmission is full. Replace the oil drain bolt.
Mopeds need their oil changed more frequently than other vehicles because of the small size of their engines. Change yours every 300 to 500 miles.
The Honda Express NC50 series moped uses a 2-stroke oil and gas mix for fuel. This is not the same oil you should use in your transmission, nor should you use the transmission type oil as your gas mix or you will harm either the engine or the transmission and have to pay for repairs.