Wiseco GP Series Piston Kit with Gaskets - Yamaha YZ85 (2002-2020) - 52.50mm Bore (+5.50mm BIG BORE) - 2-Stroke Race-Spec
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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.
📦 Shipping Information
In-stock items ship next business day. ModQuad parts dispatch Monday through Thursday.
Made-to-order and custom powder coat items show their lead time at the top of this page, right next to the truck icon. These are built fresh for you, so timing varies by brand and current backlog.
Need something by a specific date? Call us at 541-668-7503 before ordering and we will check stock and ETA on that exact part. We can often point you to an in-stock alternative from another distributor.
Questions? Contact us, we respond within 24 hours.
