MOTO-MASTER Fusion Dual-Material Steel/Aluminium Rear Sprocket (black) for YAMAHA YZ 65 2018-2026

The MOTO-MASTER Fusion (noire) dual-material steel and aluminium rear sprocket is designed for YAMAHA YZ 65 from 2018 to 2026. The rear sprocket is the large sprocket bolted to the rear wheel hub. A dual-material sprocket combines steel teeth, which resist wear, with an aluminium centre that keeps the weight down: you get the service life of steel at a weight close to that of an aluminium sprocket.

Specifications

• Brand: MOTO-MASTER
• Manufacturer part numbers: 620333246, 620333247, 620333248, 620333249, 620333250
• Chain pitch: 420
• Steel toothed ring, aluminium centre
• Available versions: 46 Teeth: ref. 620333246; 47 Teeth: ref. 620333247; 48 Teeth: ref. 620333248; 49 Teeth: ref. 620333249; 50 Teeth: ref. 620333250
• Weight: 500 g

Choosing the right number of teeth

For the same bike, go for the number of teeth of your current sprocket (it's often stamped on it). More teeth on the rear sprocket shortens the gearing: more acceleration, lower top speed. Fewer teeth lengthens it. Even one or two teeth make a clear difference; if you change a lot, the chain length may need adjusting.

When to replace it?

• Teeth worn to a point or into a hook shape, worn down on one side only.
• Chain that lifts away from the sprocket when you pull it rearwards.
• Drivetrain noise, jerkiness or a chain that jumps under load.

Check the sprocket every time you service the chain. Always replace the rear sprocket, front sprocket and chain together: a new part running with worn ones wears out very quickly.

Fitting tips

1. Clean the hub and check that it isn't cracked or distorted.
2. Fit the sprocket the right way round (markings facing out) and tighten the bolts in a criss-cross pattern to the manufacturer's torque, with medium-strength threadlocker if the manual calls for it.
3. While you're at it, replace the front sprocket and the chain if they're worn.
4. Set the chain tension as per the manual, with the wheel aligned, then lube it with a suitable chain lube.
5. Recheck the bolt tightness and the chain tension after the first ride.

Why MOTO-MASTER?

In motocross, Moto-Master was working with the Red Bull KTM Factory Racing team as early as 2010, and it backed the MXGP world championship in 2015. On the technical side, the Flame profile of its discs is designed to improve cooling and go easy on the pads, and its Racing GP sintered pads use a backing plate with hooks (NRS technology) that stops the friction material from coming away.

Spare parts and items to plan

• Front sprocket : RENTHAL 506--420-14GP · RENTHAL 506--420-14P
• Drive chain : see the selection
• Chain lube : LIQUI MOLY 400 ml · MUC OFF

Frequently asked questions

What's the advantage over an aluminium sprocket?
The steel teeth last much longer, especially in mud or sand, for barely any extra weight.

Should the chain be replaced at the same time?
Yes, if it's worn: a stretched chain wears out a new sprocket in a few hours.

Compatibility

Check the exact model and year of your bike in the list below before ordering.

Fits:
YAMAHA YZ 65 2026
YAMAHA YZ 65 2025
YAMAHA YZ 65 2024
YAMAHA YZ 65 2023
YAMAHA YZ 65 2022
YAMAHA YZ 65 2021
YAMAHA YZ 65 2020
YAMAHA YZ 65 2019
YAMAHA YZ 65 2018