4069M07450 Wiseco +3 mm Piston Kit for Yamaha XS1100 1978-1981 74.50mm 10.25:1

Wiseco +3 mm Piston Kit for Yamaha XS1100

This Wiseco +3 mm piston kit for Yamaha XS1100 models is a 74.50mm, 10.25:1 compression piston (cross-reference 4069M07450) built for big-bore top-end builds on 1978-1981 machines.

Overview

This Wiseco piston kit for Yamaha XS1100 motorcycles is a 74.50mm, +3 mm oversize piston made for bored-out cylinders and performance rebuilds. The 10.25:1 compression ratio piston kit for Yamaha XS1100 supports strong midrange pull on a classic inline four. It suits builders and shops doing a big-bore top-end job on 1978-1981 models.

Built For Performance

• 74.50mm bore size, +3 mm oversize over stock
• 10.25:1 compression ratio for strong midrange output
• Wiseco forged piston construction for durability at higher rpm
• Cross-reference 4069M07450 for easy parts matching
• Intended for use with a matching overbored cylinder
• Designed as a direct-fit piston for the XS1100 top end

Fits These Machines

• for Yamaha XS1100, 1978-1981

On-The-Job Use

• Big-bore rebuilds on classic XS1100 inline fours
• Restoring compression on worn or scored cylinders
• Shop engine builds requiring an oversize piston
• Street and touring use where midrange torque matters

Specs At A Glance

Good To Know

Q: Can this piston drop into a stock XS1100 cylinder? A: No, a +3 mm oversize piston requires the cylinder to be bored and honed to the matching 74.50mm size. Have the machine work done by a qualified shop before assembly.

Q: Do I need to rejet the carbs after fitting this kit? A: Higher compression and displacement often change fueling needs, so carburetor jetting should be checked and adjusted as required. Confirm clearances and ring end gaps against Wiseco specifications for your build.

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