For 2005-21 Yamaha YZ125 YZ 125 54mm Bore Cylinder Top End Piston Kit w/ Gasket

54mm Bore Cylinder Top End Piston Kit for Yamaha YZ125

The 54mm bore cylinder top end piston kit is a complete rebuild set for Yamaha YZ125 models, pairing a 54mm cylinder with a matching piston, rings, wrist pin, and gaskets to restore compression on the top end.

Overview

This 54mm bore cylinder top end piston kit gives Yamaha YZ125 owners a full top end replacement in one package. The cylinder and matching piston work together to seal the combustion chamber and restore the compression a tired two stroke loses over time. It is aimed at riders and shops rebuilding 2005 through 2021 YZ125 machines that are due for a fresh top end.

Built For Performance

• 54mm bore cylinder sized to match the included piston
• Piston kit includes rings, wrist pin, and circlips for assembly
• Gasket set included for sealing the top end during rebuild
• Cylinder bore machined for consistent ring seal and compression
• Designed as a direct fit replacement for the listed YZ125 years

Fits These Machines

• for Yamaha YZ125 2005-2021

On-The-Job Use

• Top end rebuilds when compression has dropped or the piston is scored
• Motocross and trail riding where fresh top end power matters
• Rebuilds after a seizure or lean condition has damaged the piston
• Routine refresh cycles on a two stroke race bike

Specs At A Glance

Good To Know

Q: What else should I replace during a top end rebuild? A: It is common to inspect the small end bearing, power valve, and coolant hoses while the cylinder is off. Replacing the small end bearing alongside the piston is standard practice.

Q: Do I need to check piston to cylinder clearance? A: Yes, clearance should be measured against the spec for your model before assembly. Verify ring end gap as well so the new top end breaks in correctly.

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