232M08550 Wiseco .020 Piston Kit for Yamaha DT400 MX400 1975-1978 85.50 mm

Wiseco .020 Piston Kit for Yamaha DT400 & MX400

This Wiseco .020 oversize piston kit, part 232M08550, is a top-end replacement piston and ring assembly built for a bored cylinder with an 85.50 mm diameter.

Overview

This Wiseco piston kit is made for the Yamaha DT400 and MX400 from 1975 through 1978, giving you a fresh top end with an 85.50 mm oversize piston. The kit is intended for riders and mechanics rebuilding a worn or seized engine where the cylinder has been bored out to the next size. If you are servicing a DT400 or MX400 top end, this Wiseco piston kit delivers the precision fit these vintage machines need.

Built For Performance

• Wiseco forged piston construction for strength and heat resistance
• .020 inch oversize 85.50 mm bore size for reconditioned cylinders
• Kit includes piston, rings, wrist pin, and circlips for a complete top-end refresh
• Precision machining supports consistent ring seal and compression
• Designed specifically for the Yamaha DT400 and MX400 engine family
• Part number 232M08550 for easy reference and ordering

Fits These Machines

• for Yamaha DT400 1975-1978
• for Yamaha MX400 1975-1978

Good To Know

Q: What does the .020 oversize mean? A: It is a 0.020 inch oversize piston at 85.50 mm, so it requires a cylinder bored and honed to match that diameter. Q: Is this a complete top-end kit? A: It includes the piston, rings, wrist pin, and circlips needed for piston replacement, though gaskets and bearings may be sold separately.

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