This jet is identified by the numbers 454 being stamped on it but you may also find that there are other needle jets that though having a different series number stamped on them, are in fact identical to the 454 and thus interchangeable. The 454 series are used in our TM24 carb but usually not in the original equipment versions of these carburetors found on production bikes. These NJ’s use a HEX 4/042 type main jet which is a different thread and sizing scale than the round type main jets.
The lower the letter and number indicates the leaner the jet. Example N-6 is leaner than N-8. These are in 0.01mm increments and the 1/2 size 5’s are in a 0.005mm increments. Only the shown sizes are available.