478M08700 Wiseco Std Piston Kit for Yamaha YZ490 IT490 1982-1984 87.00 mm

Wiseco Std Piston Kit for Yamaha YZ490 & IT490

This standard bore piston kit is a direct-fit replacement for the 1982-1984 Yamaha YZ490 and IT490, restoring compression and top-end power with the OEM cross-reference 478M08700 at a 87.00 mm bore size.

Overview

This Wiseco Std Piston Kit for Yamaha YZ490 & IT490 is a standard bore replacement piston assembly engineered for 1982-1984 models. It restores lost compression and top-end performance after a rebuild or top-end service. Riders and mechanics working on vintage Yamaha two-strokes will find this piston kit a dependable choice for keeping the 490 engine running strong.

Built For Performance

• Standard 87.00 mm bore size for OEM-equivalent fitment
• Forged piston construction for strength under high-rpm conditions
• Kit includes piston, rings, wrist pin, and circlips for a complete top-end rebuild
• Cross-references OEM part number 478M08700
• Designed specifically for 1982-1984 Yamaha YZ490 and IT490 applications
• Precision machined for consistent bore clearance and ring seal

Fits These Machines

• for Yamaha YZ490 1982
• for Yamaha YZ490 1983
• for Yamaha YZ490 1984
• for Yamaha IT490 1982
• for Yamaha IT490 1983
• for Yamaha IT490 1984

On-The-Job Use

• Top-end rebuilds on vintage Yamaha 490 two-strokes
• Restoring compression after ring wear or piston scoring
• Motocross and trail riding on YZ490 and IT490 models
• Workshop service on 1982-1984 Yamaha big-bore machines
• Keeping classic Yamaha engines in reliable running condition

Specs At A Glance

Good To Know

Q: Is this a standard bore piston? A: Yes, this kit uses the 87.00 mm standard bore size and matches the OEM 478M08700 specification for 1982-1984 Yamaha YZ490 and IT490 engines.

Q: What comes in the kit? A: The kit includes the piston, rings, wrist pin, and circlips needed for a complete top-end rebuild on compatible Yamaha 490 models.

Slight variation in finish or dimensions may occur between production runs, and fit can depend on serial number, so confirm compatibility before ordering.