ATHENA Cast Piston for KTM EXC, SX, XCW 125, HUSQVARNA TC, TE, TX 125, GAS GAS EC, MC 125 and HUSABERG TE 125 2001-2026

ATHENA offers this piston kit for KTM EXC, SX, XCW 125, HUSQVARNA TC, TE, TX 125, GAS GAS EC, MC 125 and HUSABERG TE 125 2001-2026. The piston slides in the cylinder and takes the force of the air-fuel combustion, passing it to the connecting rod and crankshaft.

Why a cast piston?

A cast piston is moulded from a high-silicon aluminium alloy, then machined.

• Low expansion: it runs with a tight clearance, stays quiet when cold and warms up quickly.
• Durability: an excellent choice for a stock engine used for leisure or enduro.
• Price: more affordable than a forged piston.
• Good to know: it copes less well with overheating and extreme revs than a forged one.

Why choose ATHENA?

Athena, the Italian manufacturer founded in 1973, is an original-equipment supplier to manufacturers such as KTM and Ducati: the same standards for your replacement parts.

When should you replace the piston on your KTM SX 125?

Harder starting, loss of power, blue smoke, oil consumption or a knock when cold: these are the signs of a tired top end.

No manufacturer hour figure for this model. Cross-Mania guideline: compression check every 20 h in hard use and every 40 h for leisure.

Specifications and fitting tips

• Engine: 2-stroke
• Manufacturer part numbers: S4C05400027A (A), S4C05400027B (B), S4C05400027C (C), S4C05400027D (D)

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 53.94 mm, B = 53.95 mm, C = 53.96 mm, D = 53.97 mm.

Spare parts and items to plan

• Piston rings : VERTEX · WISECO
• Piston pin : VERTEX · WOSSNER
• Top-end gasket kit : ATHENA · CENTAURO
• Small end needle bearing : PROX · NTN
• Spark plug : NGK 2707 · NGK 3006
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 2-stroke oil : LIQUI MOLY 1 L · MOTUL 1 L

Compatibility

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

Fits:
GAS GAS EC 125 2025
GAS GAS MC 125 2026
GAS GAS MC 125 2025
GAS GAS MC 125 2024
GAS GAS MC 125 2023
GAS GAS MC 125 2022
GAS GAS MC 125 2021
HUSABERG TE 125 2014
HUSABERG TE 125 2013
HUSABERG TE 125 2012
HUSABERG TE 125 2011
HUSQVARNA TC 125 2026
HUSQVARNA TC 125 2025
HUSQVARNA TC 125 2024
HUSQVARNA TC 125 2023
HUSQVARNA TC 125 2022
HUSQVARNA TC 125 2021
HUSQVARNA TC 125 2020
HUSQVARNA TC 125 2019
HUSQVARNA TC 125 2018
HUSQVARNA TC 125 2017
HUSQVARNA TC 125 2016
HUSQVARNA TC 125 2015
HUSQVARNA TC 125 2014
HUSQVARNA TE 125 2026
HUSQVARNA TE 125 2025
HUSQVARNA TE 125 2017
HUSQVARNA TE 125 2016
HUSQVARNA TE 125 2015
HUSQVARNA TE 125 2014
HUSQVARNA TX 125 2019
HUSQVARNA TX 125 2018
KTM EXC 125 2016
KTM EXC 125 2015
KTM EXC 125 2014
KTM EXC 125 2013
KTM EXC 125 2012
KTM EXC 125 2011
KTM EXC 125 2010
KTM EXC 125 2009
KTM EXC 125 2008
KTM EXC 125 2007
KTM EXC 125 2006
KTM EXC 125 2005
KTM EXC 125 2004
KTM EXC 125 2003
KTM EXC 125 2002
KTM EXC 125 2001
KTM SX 125 2026
KTM SX 125 2025
KTM SX 125 2024
KTM SX 125 2023
KTM SX 125 2022
KTM SX 125 2021
KTM SX 125 2020
KTM SX 125 2019
KTM SX 125 2018
KTM SX 125 2017
KTM SX 125 2016
KTM SX 125 2015
KTM SX 125 2014
KTM SX 125 2013
KTM SX 125 2012
KTM SX 125 2011
KTM SX 125 2010
KTM SX 125 2009
KTM SX 125 2008
KTM SX 125 2007
KTM SX 125 2006
KTM SX 125 2005
KTM SX 125 2004
KTM SX 125 2003
KTM SX 125 2002
KTM SX 125 2001
KTM XCW 125 2026
KTM XCW 125 2025
KTM XCW 125 2019
KTM XCW 125 2018