RFX Race 13 Teeth Gearbox output pinionRef : RFX00558A / 1123287001

RFX Race Sprocket 13 Teeth — designed for motocross use, this RFX front sprocket is CNC machined from robust alloy steel, then carburized to achieve a hardness of approximately 60 HRC to limit wear on demanding terrains. Silver finish and standard version: a reliable choice for adjusting the gearing of your 428 transmission.

• Manufacturer Reference: FXFS 51-13 55ST
• Number of Teeth: 13
• Chain Pitch: 428
• Material: Carburized alloy steel
• Machining: CNC with tight tolerances for precise fit on the shaft
• Finish: silver color, standard version
• Some RFX sprockets include lightweight holes on certain models to reduce mass without compromising strength.

This sprocket is intended for motocross pistons and setups where you want to adjust the final ratio (traction vs speed). Compatible with many 85–125 cc bikes used in motocross, it fits models such as KTM 85 SX STD WHEELS 17/14 (2025), Husqvarna TC 85 STD WHEELS 17/14 (2023), or Beta Evo 80 2T Senior (2020) depending on necessary mounting and spacers.

Easy installation as a replacement for a standard front sprocket: make sure to check the chain/sprocket alignment and longitudinal play before restarting.