WOSSNER piston kit for KTM EXC 250, MXC 250 from 2000 to 2005

WOSSNER offers this piston kit for KTM EXC 250, MXC 250 from 2000 to 2005. 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 WOSSNER?

Wössner has forged its own pistons since 1994: Molykote-coated skirt to reduce friction and ease running-in, kit supplied complete with rings, pin and clips.

When should you replace the piston on your KTM EXC 250?

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

• Displacement: 250 cm³
• Stroke: 72.00 mm
• Piston material: Aluminium alloy, Forged
• Ring material: Nitride coating, Steel, Cast
• Skirt coating: Molybdenum disulphide
• Forged piston: aerospace-grade aluminium alloy, closed-die forged for high tensile and fatigue strength

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 66.40 mm, B = 66.41 mm.

Cross-Mania tip: Measure the cylinder bore before ordering: the piston must match your cylinder size. Follow the manufacturer's break-in procedure and replace the top-end gaskets at the same time.

Also needed with this part

• Top-end gasket kit : ATHENA · PROX
• Spark plug : NGK · NGK 13 g
• 2-stroke oil : LIQUI MOLY 1 L 3065 · LIQUI MOLY 1 L 3063
• Air filter : ATHENA · TECNIUM

Compatibility

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

Fits:
KTM EXC 250 2005
KTM EXC 250 2004
KTM EXC 250 2003
KTM EXC 250 2002
KTM EXC 250 2001
KTM EXC 250 2000
KTM MXC 250 2005
KTM MXC 250 2004
KTM MXC 250 2003
KTM MXC 250 2002
KTM MXC 250 2001
KTM MXC 250 2000