ATHENA Racing Forged Piston ref. S4F09500004 for KTM EXC, MXC, SX 520, 525 and BETA RR 525 2000-2009

ATHENA offers this piston kit for KTM EXC 520, EXC 525, MXC 520, MXC 525, SX 520, SX 525 and BETA RR 525 2000-2009. 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 520?

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 50 h in hard use and every 100 h for leisure.

Specifications and fitting tips

• Engine: 4-stroke
• Manufacturer part numbers: S4F09500004A (A), S4F09500004B (B)

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 94.94 mm, B = 94.95 mm.

Spare parts and items to plan

• Piston rings : VERTEX · WOSSNER
• Piston pin : WOSSNER
• Top-end gasket kit : ATHENA · CENTAURO
• Spark plug : see the selection
• Coolant : LIQUI MOLY 1 L · TWIN AIR
• 4-stroke engine oil : LIQUI MOLY 10W40 1 L · MOTUL 10W50

Compatibility

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

Fits:
BETA RR 525 2009
BETA RR 525 2008
BETA RR 525 2007
BETA RR 525 2006
BETA RR 525 2005
KTM EXC 520 2009
KTM EXC 520 2008
KTM EXC 520 2007
KTM EXC 520 2006
KTM EXC 520 2005
KTM EXC 520 2004
KTM EXC 520 2003
KTM EXC 520 2002
KTM EXC 520 2001
KTM EXC 520 2000
KTM EXC 525 2009
KTM EXC 525 2008
KTM EXC 525 2007
KTM EXC 525 2006
KTM EXC 525 2005
KTM EXC 525 2004
KTM EXC 525 2003
KTM EXC 525 2002
KTM EXC 525 2001
KTM EXC 525 2000
KTM MXC 520 2009
KTM MXC 520 2008
KTM MXC 520 2007
KTM MXC 520 2006
KTM MXC 520 2005
KTM MXC 520 2004
KTM MXC 520 2003
KTM MXC 520 2001
KTM MXC 520 2000
KTM MXC 525 2009
KTM MXC 525 2008
KTM MXC 525 2007
KTM MXC 525 2006
KTM MXC 525 2005
KTM MXC 525 2004
KTM MXC 525 2003
KTM MXC 525 2002
KTM MXC 525 2001
KTM MXC 525 2000
KTM SX 520 2009
KTM SX 520 2008
KTM SX 520 2007
KTM SX 520 2006
KTM SX 520 2005
KTM SX 520 2004
KTM SX 520 2003
KTM SX 520 2002
KTM SX 520 2001
KTM SX 520 2000
KTM SX 525 2009
KTM SX 525 2008
KTM SX 525 2007
KTM SX 525 2006
KTM SX 525 2005
KTM SX 525 2004
KTM SX 525 2003
KTM SX 525 2002
KTM SX 525 2001
KTM SX 525 2000