85cc Cylinder Piston Gasket Top End Kit for 2002-2020 Yamaha YZ85 4ES-11311-30

85cc Cylinder Piston Gasket Top End Kit for Yamaha YZ85

This 85cc top end kit for Yamaha YZ85 combines a cylinder, piston, and gasket set to restore compression and top end power, with the cylinder cross-referencing OEM part number 4ES-11311-30 for straightforward replacement.

Overview

The 85cc Cylinder Piston Gasket Top End Kit for Yamaha YZ85 delivers the core components needed to rebuild a worn or damaged top end in one package. It restores compression, combustion efficiency, and usable power so the bike runs cleanly through the rev range. This YZ85 top end kit suits riders and mechanics handling routine rebuilds or mid-season refreshes on 2002-2020 machines.

Built For Performance

• Cylinder, piston, and gasket set supplied together for a complete top end rebuild
• Cylinder casting cross-references OEM part number 4ES-11311-30 for fitment confirmation
• 85cc displacement matches the stock YZ85 bore and stroke
• Gasket set seals the cylinder base, head, and related joints during assembly
• Components produced to dimensional tolerances that support consistent compression

Fits These Machines

• for Yamaha YZ85 2002
• for Yamaha YZ85 2003
• for Yamaha YZ85 2004
• for Yamaha YZ85 2005
• for Yamaha YZ85 2006 through 2020 model years

On-The-Job Use

• Top end rebuilds after a piston seize or loss of compression
• Scheduled maintenance on motocross and trail ridden YZ85 machines
• Refreshing a used bike before a season of riding
• Rebuilding a race bike between events

Specs At A Glance

Good To Know

Q: Does this kit include everything needed for a top end rebuild? A: It supplies the cylinder, piston, and gasket set, so check the listing contents against any bearings, clips, or small parts your service manual calls for. A: Measure the old bore and confirm your model year uses the 4ES-11311-30 cylinder before ordering.

Q: Can I install this myself? A: A top end rebuild calls for basic mechanical skill, a torque wrench, and clean assembly practices. Follow the factory service specs for torque values and break-in.

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