For my 1996 RMX, my manual states (not sure if the 1998 is the same):
Main Jet = #165
Slow jet = #60
Jet Needle = R1472M1L
Needle position = 3rd
Air screw = 1 turn out
Manual also states:
Bore = 38 mm
Cut-away = 5
Float Height = 16.1 +/- 1.0 mm (0.63 +/- 0.01 in)
For my 1996 RMX, my manual states (not sure if the 1998 is the same):
Main Jet = #165
Slow jet = #60
Jet Needle = R1472M1L
Needle position = 3rd
Air screw = 1 turn out
Manual also states:
Bore = 38 mm
Cut-away = 5
Float Height = 16.1 +/- 1.0 mm (0.63 +/- 0.01 in)