VERTEX piston kit for YAMAHA WR 250 F, YZ 125 X, YZ 250 F, FANTIC XEF 250, XXF 250 and HUSQVARNA TX 300 from 2019 to 2026

VERTEX offers this piston kit for YAMAHA WR 250 F, YZ 125 X, YZ 250 F, FANTIC XEF 250, XXF 250 and HUSQVARNA TX 300 from 2019 to 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 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 VERTEX?

Vertex has made its pistons in Italy since 1953 and has supplied KTM’s original pistons since 1996: molybdenum-disulphide coated skirt and Japanese rings. Its two-stroke pistons are cast from an 18 % silicon alloy. Its four-stroke pistons are forged from 2618 alloy.

When should you replace the piston?

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

Recommended hours for a top-end rebuild (manufacturer recommendation for the KTM EXC / XC-W, Husqvarna TE 250/300 2017-2023):

• Racing: every 40 h.
• Leisure: every 80 h.
• KTM EXC, Husqvarna TE, GASGAS EC two-strokes since 2024: racing and leisure: every 45 h.

Specifications and fitting tips

• Displacement: 250 cm³
• Piston material: Aluminium alloy, Forged
• Ring material: Nitride coating, Steel
• Skirt coating: Molybdenum coating
• Style: Forged Replica
• Pro-Replica: forged piston with the original shape

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore).

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 S410485015037 · ATHENA P400485160006
• Spark plug : NGK 8 g · NGK
• 4-stroke engine oil : LIQUI MOLY 10W40 1 L · MOTUL 10W50
• Air filter : TWIN AIR · TWIN AIR over-filter for FANTIC XE, XX…

Compatibility

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

Fits:
FANTIC XEF 250 2025
FANTIC XEF 250 2024
FANTIC XEF 250 2023
FANTIC XEF 250 2022
FANTIC XXF 250 2026
FANTIC XXF 250 2025
FANTIC XXF 250 2024
FANTIC XXF 250 2023
FANTIC XXF 250 2022
HUSQVARNA TX 300 I 2024
HUSQVARNA TX 300 I 2023
HUSQVARNA TX 300 I 2022
HUSQVARNA TX 300 I 2021
HUSQVARNA TX 300 I 2020
YAMAHA WR 250 F 2026
YAMAHA WR 250 F 2025
YAMAHA WR 250 F 2024
YAMAHA WR 250 F 2023
YAMAHA WR 250 F 2022
YAMAHA WR 250 F 2021
YAMAHA WR 250 F 2020
YAMAHA YZ 125 X 2022
YAMAHA YZ 125 X 2021
YAMAHA YZ 125 X 2020
YAMAHA YZ 250 F 2026
YAMAHA YZ 250 F 2025
YAMAHA YZ 250 F 2024
YAMAHA YZ 250 F 2023
YAMAHA YZ 250 F 2022
YAMAHA YZ 250 F 2021
YAMAHA YZ 250 F 2020
YAMAHA YZ 250 F 2019
YAMAHA YZ 250 FX 2022
YAMAHA YZ 250 FX 2021
YAMAHA YZ 250 FX 2020