HONDA EXPRESS NC 50
If you want your honda express to do a genuine 45-50 mph . Day in day out have a go at these jobs.
1) first locate a kawasaki ar 50 micron exhaust.
2) then find a suzuki ap 50 carburetta.
3) take off the standard airbox and carb, and fit the ap 50 carb. you will have to file the mounting holes on the inlet manifold slightly, but the holes in the carb and the inlet should match up spot on.
4) remove the exhaust and cut the pipe just before it goes into the silencer.
5) next take the cylinder and head off. if you take the cylinder and look down the barrel as the piston travels ie ; from the bottom, you will see the transfer ports( this is where the fuel air mix comes up from the crankcase to be burned.
see if you can locate a small elecric grinder ( like a dremmel) put in a grinding stone or carbon cutting tool, and take off all the rough casting marks from the ports. be very carefull not to damage the surface in the barrel where the piston runs.
6) while the barel is off make a duplicate base gasket out of 2mm aluminium or very hick gasket paper.
7) once you have done that clean the barrel out with petrol and put a light coat of 2 stroke oil in the barrel and on the piston. also on your new base gasket.
8) refit the barrel. carefull not to break the piston rings.
9) before refitting the cylinder head get some grinding paste( like the kind for lapping in valves) and a peice of glass bigger than the head.
cover the face of the head where it mates with the cylinder and rub the head flat on the glass.
10) clean the head and replace the plug if you left it in. refit the head without the copper gasket.
11) find a friend with a welder and get him to weld the ar 50 micron exhuast onto the standard pipe you cut from the silencer. make sure you put it at an angle at which you can make a bracket to hold it.
12) fit about a 65 slot headed main jet ( you will have to check how this runs dependant on temperature in your country , the whiter the plug colour the richer you will need to go on the main jet ,bigger number relates to more fuel)
13) fill her up with fuel you will probarbly need to use premix at about 30 to 1
14 ride and enjoy a mutch faster express (25 mph ha)