Wiseco GP Series Piston Kit with Gaskets - Yamaha YZ125 / YZ125X (2005-2022) - 56.00mm Bore (+2.00mm BIG BORE) - 2-Stroke Race-Spec

Wiseco GP Series Piston Kit with Gaskets - Yamaha YZ125 / YZ125X - BIG BORE

The Wiseco GP Series represents the pinnacle of 2-stroke piston technology for the legendary Yamaha YZ125. This is a BIG BORE kit (+2.00mm) that increases displacement from 125cc to 134cc - giving your YZ125 significant power gains while maintaining the GP Series race-spec features!

🔥 BIG BORE: 125cc → 134cc (+7.2%!)

This +2.00mm big bore kit provides a 9cc displacement increase - that's 7.2% more displacement for noticeably improved power throughout the rev range!

🏁 GP Series Race-Spec Features

• Electra Coating - Crown, ring groove(s), and pin bores coated for maximum wear resistance
• ArmorGlide® Skirt Coating - Protection from micro-welding, galling, and detonation
• Extra Lightening Operations - Enhanced throttle response
• Made in USA - Engineered, forged, and machined in the USA

Kit Includes

• Wiseco GP Series Piston - Premium 4032 aluminum alloy with Electra + ArmorGlide®
• Ring Set
• Wrist Pin
• Circlips
• Wrist Pin Bearing
• Top End Gasket Set

Key Features

• GP Series design for professional-level racing performance
• 4032 aluminum alloy construction - optimized for 2-stroke applications
• Dual coating system - Electra + ArmorGlide® for ultimate protection
• Designed for endurance and sustained RPM riding
• Complete top-end gasket kit included
• Wrist pin bearing included - everything for a complete rebuild

Displacement Increase

• Stock Bore: 54.00mm = 125cc
• Big Bore: 56.00mm = 134cc (+7.2% displacement!)

Important Notes

• Cylinder must be bored to 56.00mm
• Wiseco ring types are not interchangeable
• Wiseco pistons can be fitted only with Wiseco rings
• Cylinder sleeves must be purchased separately if needed

Piston Specifications

• Bore Size: 56.00 mm (+2.00mm Big Bore)
• Piston Diameter: 55.95 mm
• Stroke Length: 54.50 mm
• Material: 4032 Aluminum Alloy
• Skirt Coating: ArmorGlide® + Electra
• Style: GP Series

Engine Specifications

• Displacement: 134cc (up from 125cc)
• Engine Type: 2-Stroke
• Weight: 0.9 lbs

Fitment

Yamaha:

• YZ125: 2005-2021 (17 years!)
• YZ125X: 2020-2022 (enduro variant)

GP Series vs Pro-Lite Big Bore

This is the GP Series 56mm big bore with race-spec Electra + ArmorGlide coatings. We also offer a Pro-Lite 56mm big bore (SKU 0903-1160) without the advanced coatings at a lower price point.

Why Wiseco GP Series Big Bore?

Combine the legendary YZ125 platform with +9cc displacement AND GP Series race technology for the ultimate competitive advantage!