MOTO-MASTER Ultralight Steel Rear Sprocket for YAMAHA TT 600, TTR 600, WR 200, WRF 400, YZ 125, YZ 250, YZF 400 1977-2003

The MOTO-MASTER steel rear sprocket is designed for YAMAHA TT 600, TTR 600, WR 200, WRF 400, YZ 125, YZ 250, YZF 400 from 1977 to 2003. Bolted to the rear wheel, the sprocket takes all of the engine's force through the chain. Steel is the choice for durability: a steel sprocket sees off several chains where an aluminium one wears out, for a little more weight.

Specifications

• Brand: MOTO-MASTER
• Manufacturer part numbers: 620131136, 620131138, 620131140
• Chain pitch: 520
• Material: steel
• Available versions: 36 Teeth: ref. 620131136; 38 Teeth: ref. 620131138; 40 Teeth: ref. 620131140
• Weight: 850 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?

Moto-Master is a Dutch brand founded in 1997 by Gaston Vernon that specialises in braking: discs, sintered pads and oversize kits. Its discs are designed in CAD and then laser-cut on CNC machines, with manufacturing in the Netherlands and ISO 9001:2015 certification.

Spare parts and items to plan

• Front sprocket : PBR 565 1 · PBR 565G 15 18NC
• Drive chain : RENTHAL · RENTHAL 520
• Chain lube : LIQUI MOLY 400 ml · SCOTTOILER

Frequently asked questions

Aluminium or steel?
Aluminium is lighter and works well for motocross and racing. Steel lasts longer: it's the best choice for enduro, sandy terrain or if you put in a lot of hours.

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 TT 600 1992
YAMAHA TT 600 1991
YAMAHA TT 600 1990
YAMAHA TT 600 1989
YAMAHA TT 600 1988
YAMAHA TT 600 1987
YAMAHA TT 600 1986
YAMAHA TT 600 1985
YAMAHA TT 600 1984
YAMAHA TT 600 1983
YAMAHA TTR 600 2003
YAMAHA TTR 600 2002
YAMAHA TTR 600 2001
YAMAHA TTR 600 2000
YAMAHA TTR 600 1999
YAMAHA TTR 600 1998
YAMAHA WR 200 1992
YAMAHA WR 200 1991
YAMAHA WRF 400 1998
YAMAHA YZ 125 1998
YAMAHA YZ 125 1997
YAMAHA YZ 125 1996
YAMAHA YZ 125 1995
YAMAHA YZ 125 1994
YAMAHA YZ 125 1993
YAMAHA YZ 125 1992
YAMAHA YZ 125 1991
YAMAHA YZ 125 1990
YAMAHA YZ 125 1989
YAMAHA YZ 125 1988
YAMAHA YZ 125 1987
YAMAHA YZ 125 1986
YAMAHA YZ 125 1985
YAMAHA YZ 125 1984
YAMAHA YZ 125 1983
YAMAHA YZ 125 1982
YAMAHA YZ 125 1981
YAMAHA YZ 125 1980
YAMAHA YZ 250 1998
YAMAHA YZ 250 1997
YAMAHA YZ 250 1996
YAMAHA YZ 250 1995
YAMAHA YZ 250 1994
YAMAHA YZ 250 1993
YAMAHA YZ 250 1992
YAMAHA YZ 250 1991
YAMAHA YZ 250 1990
YAMAHA YZ 250 1989
YAMAHA YZ 250 1988
YAMAHA YZ 250 1987
YAMAHA YZ 250 1986
YAMAHA YZ 250 1985
YAMAHA YZ 250 1984
YAMAHA YZ 250 1983
YAMAHA YZ 250 1982
YAMAHA YZ 250 1981
YAMAHA YZ 250 1980
YAMAHA YZ 250 1979
YAMAHA YZ 250 1978
YAMAHA YZ 250 1977
YAMAHA YZF 400 1998