- New
ATHENA Racing Forged Piston for KTM EXC 125, SX 125 1987-1993
€146.90
Tax Included
The piston moves up and down in the cylinder to turn combustion into motion: this kit replaces it along with its rings, pin and clips.
Available in several sizes.
ATHENA offers this piston kit for KTM EXC 125, SX 125 1987-1993. The piston slides in the cylinder and takes the force of the air-fuel combustion, passing it to the connecting rod and crankshaft.
Why choose a forged piston?
Instead of simply being cast, a forged piston is hot-pressed under very high pressure and then machined: its metal is denser and free of air pockets.
- Stronger when hot: it copes better with high revs, overheating and detonation.
- Lighter for the same strength: less stress on the connecting rod and bearings.
- Good to know: depending on the alloy, it expands a little more and is fitted with more clearance; slight noise when cold is normal.
- Why does it cost more? Forging tools, full machining and surface treatments cost more than simple casting.
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 EXC 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: S4F05425001A (A), S4F05425001B (B), S4F05425001C (C)
Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 54.19 mm, B = 54.20 mm, C = 54.21 mm.
Spare parts and items to plan
- Piston rings : PROX 02.6225 · PROX 02.6220
- 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:
KTM EXC 125 1993
KTM EXC 125 1992
KTM EXC 125 1991
KTM EXC 125 1990
KTM EXC 125 1989
KTM EXC 125 1988
KTM EXC 125 1987
KTM SX 125 1993
KTM SX 125 1992
KTM SX 125 1991
KTM SX 125 1990
KTM SX 125 1989
KTM SX 125 1988
KTM SX 125 1987
S4F05425001A
5 Items
Specific References
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The piston moves up and down in the cylinder to turn combustion into motion: this kit replaces it along with its rings, pin and clips.
Available in several sizes.
ATHENA Racing Forged Piston for KTM EXC 125, SX 125 1987-1993
€146.90
Tax Included