I am going to outline some suggested steps in order to remove and clean a 1978 Honda Express nc moped carburetor, and they reinstall it. I hopefully will include photos I have taken to document the process. I find the photos are good demonstration tools to help others follow along or correctly put things back together if you forgot how you took it apart on a '78 Express motor bike.
- Shut Off Fuel - Turn the fuel value to OFF that is attached to the moped's petcock.
- Put Container Under Moped - I happened to have a large plastic sheet that I put under my express moped to protect and collect any fuel that spilled when doing maintenance. You could use card board, plastic tub, newspapers, whatever to catch any spills.
- Stay Away From Flames - Do do your honda moped maintenance near flames or anything that could ignite the gasoline fumes. Don't DIE working on your moped.
- Remove Air Cleaner Covering, Foam Air Filter, Filter Unit - See pictures below. Also, note that there is no foam 1978 nc50 Honda Express Air Filter/Cleaner on the table. That was because the previous owner never put it back on!
- Remove Throttle, Choke Attachment, and Fuel Line - Carefully unwind the plastic honda express throttle cord attachment. The nc50 choke cord attachment to carburetor will require a adjustable wrench to remove. Finally uncrimp the little tensioner ring around the rubber fuel line that is attached to the moped carburetor. You will find out quickly if you forgot to shut off the fuel, because gasoline will come spilling out everywhere. Granted, you will get some gasoline spilling out because there is still fuel in rubber line.
- Remove Carburetor Itself - There are three bolts holding the Express Honda carburetor in place. Once the bolts are removed, it should freely be taken out. Gasoline fuel will continue to spill out that is left in carburetor.
- Clean The Carburetor - BE CAREFUL NOT TO LOOSE YOUR HONDA EXPRESS NC 50 FLOAT PIN. The part is very small and will cost you if you loose it! I used "STP Carburetor Cleaner" to clean the moped carb. You can find the product at many local PepBoys or AutoZone.
- Inspect The Components - Take care to inspect the moped's plastic float, rubber honda moped gasket ring, express float pin, and honda express carb main jet. Take care to use a can of compressed air and blow out the valves and make sure they are not obstructed. When the carburetor is put back together you don't want any water left in it. Get it dry as a bone. You could remove and clean the throttle stop screw and/or the moped air screw, but I didn't. I figured they were set properly before and I didn't need the hassle of re-calibrating it.
- Reassemble Carb Components - Should only take a few minutes once they are cleaned and dried. Just reverse the steps taken to remove it. Once I reinstalled the carburetor onto the Honda moped express frame and connected the fuel line, I opened the drain screw in the float bowl. When I turned the fuel lever to ON this allowed the fuel to fill the float blow and "bleed" out the air. Probably didn't need to do that, but I did and it worked.