222M04750 .020 Piston Kit for Yamaha GT1 MX80 1973-1982 47.50 mm

Wiseco Piston Kit for Yamaha GT1 & MX80

This Wiseco 222M04750 piston kit, sized at 47.50 mm with a .020 oversize bore, is a forged replacement piston assembly for Yamaha GT1 and MX80 engines and brings compression and cylinder sealing back to spec.

Overview

This Wiseco piston kit for Yamaha GT1 and MX80 models, part 222M04750, delivers a forged piston and matching components sized at 47.50 mm for a .020 oversize bore. The piston kit suits riders and mechanics rebuilding worn top ends on 1973 to 1982 Yamaha GT1 and MX80 engines. Each piston kit follows Wiseco 222M series dimensions for a clean fit in a freshly honed cylinder.

Built For Performance

• Forged aluminum piston construction for strength under combustion heat and load
• 47.50 mm diameter sized for a .020 oversize cylinder bore
• Wiseco 222M04750 part number identifies the exact piston and ring configuration
• Designed for the Yamaha GT1 and MX80 1973 to 1982 engine family
• Kit format includes the piston and matching components for a top-end rebuild
• Oversize bore sizing restores cylinder wall clearance after honing or reboring

Fits These Machines

• for Yamaha GT1
• for Yamaha MX80

On-The-Job Use

• Top-end rebuilds on worn or scored Yamaha GT1 and MX80 cylinders
• Restoring compression after ring wear or light scoring
• Oversize rebore service on a cylinder that needs a slight cleanup hone
• Vintage two-stroke engine refresh on 1973 to 1982 Yamaha machines

Specs At A Glance

Good To Know

Q: Will this piston fit a standard bore cylinder? A: No, this piston is sized at 47.50 mm for a .020 oversize bore, so the cylinder must be bored or honed to match that clearance before assembly.

Q: What else should I replace during the rebuild? A: Pair this Yamaha GT1 or MX80 piston kit with fresh gaskets, a wrist pin bearing, and a cylinder hone to spec so ring seal and compression come back properly.

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