Wiseco GP Series Piston Kit with Gaskets - Yamaha YZ85 (2002-2020) - 52.50mm Bore (+5.50mm BIG BORE) - 2-Stroke Race-Spec

Wiseco GP Series Piston Kit with Gaskets - Yamaha YZ85 - BIG BORE

The Wiseco GP Series represents the pinnacle of 2-stroke piston technology for the Yamaha YZ85. This is a BIG BORE kit (+5.50mm) that increases displacement from 85cc to 103.5cc - giving your YZ85 serious power gains! Engineered for endurance racing and sustained high-RPM operation with advanced coatings and extra lightening operations.

⚠️ Important: Big Bore Kit Requirements

This is a +5.50mm BIG BORE kit. Installation requires:

• Sleeving or Replating Required - Cylinder must be bored to 52.50mm
• Crankcase Clearance Required - Larger piston diameter may require crankcase modification

🏁 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: 47.00mm = 85cc
• Big Bore: 52.50mm = 103.5cc (+21.7% displacement!)

Piston Specifications

• Bore Size: 52.50 mm (+5.50mm Big Bore)
• Piston Diameter: 52.45 mm
• Stroke Length: 47.80 mm
• Material: 4032 Aluminum Alloy
• Skirt Coating: ArmorGlide® + Electra
• Style: GP Series

Engine Specifications

• Displacement: 103.5cc (up from 85cc)
• Engine Type: 2-Stroke
• Weight: 0.75 lbs

Fitment

• Yamaha YZ85: 2002-2020 (19 years!)

Why Go Big Bore?

The +5.50mm big bore conversion gives your YZ85 an 18.5cc displacement increase - that's nearly 22% more displacement! Combined with the GP Series race-spec features, this kit transforms your YZ85 into a serious competitor.