NOZZLE, MAIN, USED. Ultrasonically cleaned & measured by truing the O.D. in an adjustable chuck, then checking the internal runout. Mikuni makes needle jets in 0.0002" size increments, which yields a difference of ~0.25% CO, which is approximately equivalent to the same change that a 1/4 of a jet size produces at the combination of throttle position and rpm it most strongly affects. In other words, a needle jet that is worn by 0.0008" will change the mixture by ~ one jet size, with the predominant effect at low rpm. These motorcycles already have low rpm richness problems (once up off of idle), and needle jet wear exacerbates the issue.

Note: Image for reference only, and may not be representative. Exterior of some needle jets may exhibit discoloration/corrosion, which will not affect operation.