Prox Main Jet for Mikuni Carburetor Size 420

ProX main jet for Mikuni Carburetor size 420 (part number 47.420 / 47.420/1) is a precision main jet (main jet) from the Japanese brand ProX, perfect for fine-tuning fuel delivery in Mikuni carburetors.

This high-quality jet from the 4/042-series (large hex style) is a reliable, exact-fit replacement for original Mikuni parts. Ideal for motocross riders, enduro enthusiasts, and tuners who want to adjust jetting to match altitude, temperature, modifications such as exhaust, airbox, piston, or full engine builds. Size 420 often delivers the correct richer mixture in the mid-to-high RPM range, especially for 125cc to 300cc two-stroke engines under heavy load or in warmer conditions.