Wössner Forged Piston for BETA RR 350, RR 350 4T RACE, RR 350 4T X-PRO 2015-2026

WOSSNER offers this piston kit for BETA RR 350, RR 350 4T RACE, RR 350 4T X-PRO 2015-2026. 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 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 BETA RR 350?

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 Beta RR four-stroke):

• Normal use: every 90 h.
• Racing: no Beta figure; Cross-Mania guideline: compression check at around 45 h.

Specifications and fitting tips

• Material: Aluminium
• Specificity: Double Bridge Forging / Gas Ported
• Piston compression: Standard
• Piston type: Forged
• Rings Quantity: 2
• Forged piston

Available in several sizes: choose the one that matches your cylinder (stamped size or measured bore). Diameters: A = 87.96 mm, B = 87.97 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 : CENTAURO
• Spark plug : NGK
• 4-stroke engine oil : MOTUL 10W50 · LIQUI MOLY 10W40 1 L
• Air filter : HIFLO FILTRO · PROX

Compatibility

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

Fits:
BETA RR 350 2024
BETA RR 350 2023
BETA RR 350 2022
BETA RR 350 2021
BETA RR 350 2020
BETA RR 350 2019
BETA RR 350 2018
BETA RR 350 2017
BETA RR 350 2016
BETA RR 350 2015
BETA RR 350 4T RACE 2026
BETA RR 350 4T RACE 2025
BETA RR 350 4T X-PRO 2026
BETA RR 350 4T X-PRO 2025