09101583 PISTON KIT ALUMINUM 56.25MM +0.25MM

Name: PROX PISTON KIT ALUMINUM 56.25MM +0.25MM
Brand: PROX
SKU: 09101583
Price: 87.51 GBP
Availability: InStock

Fits 4 bikes

RRP £109.39 Save 20%

£87.51

incl. VAT

In stock — delivered in 6–10 working days

Dispatched in 2–3 working days · delivered in 6–10.

Part #: 09101583

Authorised stockist

PROX

14-day returns

Easy & hassle-free

Secure checkout

256-bit encryption

§ 02 / About this part

What it is

The PROX PISTON KIT ALUMINUM 56.25MM +0.25MM, top end. Stocked by Iron Offroad, the UK MX hard parts specialist.

Restore lost compression and engine response with this oversize top-end refresh. This component sits inside the cylinder bore, converting combustion into mechanical drive. This +0.25mm sizing is designed specifically for cylinders that have been rebored to clear scoring or ovality. It serves as a direct alternative to OEM part 3MB-11631-00. Regular replacement is essential to prevent skirt fatigue in high-hour engines. During your rebuild, verify the ring end-gap and ensure the piston arrow points toward the exhaust port. Always use new circlips and lubricate the small-end bearing thoroughly before fitting the cylinder.

§ 03 / Specs

The numbers

Brand: PROX
Part number: 09101583
Category: Top End
Weight: 0.21 kg
OEM cross-refs: 3MB-11631-00
VAT: 20%

// Fitment

Will it fit your bike?

Fits 4 models · 5 year-bands

Yamaha 5 models

* Fitment data is provided as a guide. Verify compatibility against the bike's owner's manual or service handbook before ordering. Iron Offroad accepts no liability for incorrect application. Full terms and conditions apply.

§ 05 / About Iron Offroad

Iron Offroad

Iron Offroad is the off-road sibling of Iron City and Iron Stable — a UK shop for motocross, enduro, and trail-bike hard parts. Every fitment lives on the site, listed against KTM, Husqvarna, GasGas, Yamaha, Honda, Kawasaki, Suzuki, and Beta. Pick your bike on the timing-tower. Our USP is the data: fully enriched fitment so you find the right part for your bike quickly and get it fitted accurately. Brands you'd find on a paddock workbench — pads, sprockets, plastics, fork seals, cables, gaskets, bars, the things that actually wear out. Road-bike kit, scooter parts, and quad gear sit elsewhere; dirt and e-moto only. We operate from our storage facility in Leeds. Iron Offroad is a trading name of Iron Stable Ltd, registered in Mildenhall — Company No. 17061294. The business has a rich motorcycle history across multiple moto brands — the photos show where we came from — and recently pivoted into hard parts and online retail.