PROX Forged Piston for YAMAHA WRF 450, YZF 450 and FANTIC XEF 450, XEF 450 RALLY, XXF 450 2020-2024

PROX offers this piston kit for YAMAHA WRF 450, YZF 450 and FANTIC XEF 450, XEF 450 RALLY, XXF 450 2020-2024. 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 PROX?

ProX has its pistons made in Japan and the USA, with Japanese rings (Riken, TP or NPR) and tolerances at least equal to OEM; most of its four-stroke pistons are forged.

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.

No manufacturer hour figure for this model. Cross-Mania guideline: compression check every 30 h in hard use and every 60 h for leisure.

Specifications and fitting tips

• Material: Aluminium
• Specificity: Flat Crown with Hollow Area / 4 Valve Pockets
• Piston compression: Standard
• Piston type: Forged
• Rings Quantity: Set
• Forged piston

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 96.95 mm, B = 96.96 mm, C = 96.97 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 : VERTEX · MOOSE
• Spark plug : NGK 2306 · NGK 4218
• 4-stroke engine oil : LIQUI MOLY 10W40 1 L · MOTUL 10W50
• Air filter : PROX · TECNIUM

Compatibility

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

Fits:
FANTIC XEF 450 2024
FANTIC XEF 450 2023
FANTIC XEF 450 2022
FANTIC XEF 450 RALLY 2023
FANTIC XXF 450 2023
FANTIC XXF 450 2022
YAMAHA WRF 450 2023
YAMAHA WRF 450 2022
YAMAHA WRF 450 2021
YAMAHA WRF 450 2020
YAMAHA YZF 450 2022
YAMAHA YZF 450 2021
YAMAHA YZF 450 2020