MOTO-MASTER Ultralight Front Sprocket for GAS GAS EC 250, EC 300, XC 250, XC 300 and RIEJU MR 250, MR 300 2000-2026

On GAS GAS EC 250, EC 300, XC 250, XC 300 and RIEJU MR 250, MR 300 from 2000 to 2026, the MOTO-MASTER front sprocket fits in place of the original part. Mounted on the gearbox output shaft (countershaft), the front sprocket passes the engine's torque on to the chain. Every tooth is loaded on every turn of the wheel: a worn front sprocket makes the chain jump and speeds up wear on the whole drivetrain.

Specifications

• Brand: MOTO-MASTER
• Manufacturer part numbers: 610371112, 610371113, 610371114
• Chain pitch: 520
• Material: steel
• Available versions: 12 Teeth: ref. 610371112; 13 Teeth: ref. 610371113; 14 Teeth: ref. 610371114
• Weight: 140 g
• Engine: 2-stroke

Choosing the right number of teeth

Start from the stock number of teeth. One tooth less on the front sprocket shortens the gearing (more acceleration, ideal on tight terrain); one tooth more lengthens it (more speed on fast tracks). One tooth on the front sprocket is worth roughly three to four teeth on the rear sprocket.

When to replace it?

• Teeth thinned, pointed or hooked.
• Chain that jumps or slaps under acceleration.
• Play between the sprocket and the shaft, or marked splines.

Check it every time you service the chain and replace it along with the rear sprocket and the chain. Many riders change the front sprocket with every new chain, because it wears much faster than the rear sprocket.

Fitting tips

1. Loosen the sprocket nut or bolt while holding the rear wheel with the brake, before slackening the chain.
2. Clean the countershaft and check the oil seal behind the sprocket.
3. Fit the sprocket the right way round, with a lock washer or threadlocker as on the original assembly, and tighten to the manufacturer's torque.
4. Set the chain tension and lube it with chain lube.

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

• Rear sprocket : INNTECK · JT SPROCKETS 7075
• Drive chain : RENTHAL · AFAM
• Chain lube : LIQUI MOLY 400 ml · SCOTTOILER

Frequently asked questions

Should the rear sprocket be changed too?
If it's worn, yes: a new front sprocket running on a tired rear sprocket and chain is worn out within a few hours.

Compatibility

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

Fits:
GAS GAS EC 250 2019
GAS GAS EC 250 2018
GAS GAS EC 250 2015
GAS GAS EC 250 2014
GAS GAS EC 250 2013
GAS GAS EC 250 2012
GAS GAS EC 250 2011
GAS GAS EC 250 2010
GAS GAS EC 250 2009
GAS GAS EC 250 2008
GAS GAS EC 250 2007
GAS GAS EC 250 2006
GAS GAS EC 250 2005
GAS GAS EC 250 2004
GAS GAS EC 250 2003
GAS GAS EC 250 2002
GAS GAS EC 250 2001
GAS GAS EC 250 2000
GAS GAS EC 300 2019
GAS GAS EC 300 2018
GAS GAS EC 300 2015
GAS GAS EC 300 2014
GAS GAS EC 300 2013
GAS GAS EC 300 2012
GAS GAS EC 300 2011
GAS GAS EC 300 2010
GAS GAS EC 300 2009
GAS GAS EC 300 2008
GAS GAS EC 300 2007
GAS GAS EC 300 2006
GAS GAS EC 300 2005
GAS GAS EC 300 2004
GAS GAS EC 300 2003
GAS GAS EC 300 2002
GAS GAS EC 300 2001
GAS GAS EC 300 2000
GAS GAS XC 250 2019
GAS GAS XC 250 2018
GAS GAS XC 300 2019
GAS GAS XC 300 2018
RIEJU MR 250 2026
RIEJU MR 250 2025
RIEJU MR 250 2024
RIEJU MR 250 2023
RIEJU MR 250 2022
RIEJU MR 250 2021
RIEJU MR 300 2026
RIEJU MR 300 2025
RIEJU MR 300 2024
RIEJU MR 300 2023
RIEJU MR 300 2022
RIEJU MR 300 2021