4069M07400 Wiseco +2.50 mm Piston for Yamaha XS1100 1978-1981 74mm 10.25:1 CR

Wiseco +2.50 mm Piston for Yamaha XS1100

This Wiseco +2.50 mm piston, part 4069M07400, measures 74mm and delivers a 10.25:1 compression ratio for Yamaha XS1100 engines, restoring or increasing displacement with a forged replacement that handles high cylinder pressures.

Overview

This Wiseco +2.50 mm piston is a forged replacement component built for Yamaha XS1100 engines running 1978-1981 models. The 74mm bore and 10.25:1 compression ratio make this Wiseco piston a solid choice for riders rebuilding a worn top end or refreshing a performance-oriented engine build. It suits mechanics and enthusiasts who want a reliable piston that holds up under the demands of a classic inline four.

Built For Performance

• Forged aluminum construction for higher strength than cast pistons
• 74mm bore size matches a +2.50 mm overbore for worn cylinders
• 10.25:1 compression ratio supports strong combustion efficiency
• Precision-machined ring grooves for consistent ring seal
• Part number 4069M07400 for straightforward cross-referencing

Fits These Machines

• for Yamaha XS1100 1978
• for Yamaha XS1100 1979
• for Yamaha XS1100 1980
• for Yamaha XS1100 1981

On-The-Job Use

• Top-end rebuilds on high-mileage XS1100 engines
• Cylinder overbore work when bores are scored or out of spec
• Restoration projects returning a classic inline four to service
• Performance builds seeking a higher compression ratio

Specs At A Glance

Good To Know

Q: Does this piston require machine work on the cylinder? A: Yes, a +2.50 mm overbore piston needs the cylinder bored and honed to match the 74mm size before installation.

Q: Can I install just one piston? A: It can be installed individually, though replacing pistons as a matched set is common practice on multi-cylinder engines during a rebuild.

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