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Engines and Components› Pistons and Piston Rings

ProX

Piston Kit with Ring Kit, Wrist Pin, and Circlips

$121.95 $109.76 Save $12.19

SKU: 01.2224.B

In Stock
In Stock
Ships by Nov 17
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$100 Minimum Order
Non-Returnable Item
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Overview

The ProX Piston Kit is a standard size B, 53.95mm piston designed for 2-stroke, 125cc engines. Manufactured in Japan from a high-silicon-content aluminum alloy, it meets or exceeds OEM specifications. This kit is CNC-machined to precise tolerances and includes the piston, ring kit, wrist pin, and circlips for an OEM replacement.

This piston kit features a moly-coated skirt for reduced friction and is intended for off-road riding styles. The bore size is 54.00 mm, and it maintains a standard compression ratio.
Show original supplier description
The ProX Piston Kit is a precision-machined replacement part designed to restore your Yamaha YZ 125 to optimal performance. Manufactured in Japan, this kit utilizes the same low-expansion, low-friction aluminum alloy found in major OEM components. The piston is cast from a high-silicon-content alloy, meeting or exceeding OEM specifications, and then CNC-machined for exceptional accuracy. This piston kit is designed as a direct replacement for your original parts, providing a cost-effective solution without the need for cylinder boring or replacement. The kit comes complete with the piston, ring kit, wrist pin, and circlips, ensuring you have all the necessary components for installation. ProX pistons feature OEM-style tin coating to aid in the break-in process, along with a new skirt coating that further reduces friction and can enhance performance. Specifically, this ProX Piston Kit (01.2224.B) is designed for the Yamaha YZ 125 models from 2002 to 2004. It features a standard bore size of 53.95mm, designated as Size B, and is suitable for 2-stroke engines. The product disclaimer emphasizes the importance of measuring your cylinder before ordering to ensure correct sizing, as damage or returns due to incorrect size selection will not be accepted.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandProX
Part Number01.2224.B
CategoryEngines and Components
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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