HZ Muffler Assembly Kit for Honda GX340/GX390/GX420 & Predator 420cc — direct-fit muffler and exhaust pipe with gaskets and hardwa

An all-in-one replacement muffler and exhaust pipe kit designed to restore proper exhaust fit and quieter operation on Honda GX340/GX390/GX420 and Predator 420cc clone engines.

This HZ muffler assembly kit supplies the parts needed to replace worn or damaged exhaust components on a wide range of small horizontal engines used on pressure washers, water pumps, air compressors, log splitters and other power equipment. The package combines a muffler assembly, exhaust pipe (manifold), gaskets and mounting hardware so you can swap the full assembly in one service session rather than sourcing individual pieces. It’s manufactured to match the common mounting pattern and exhaust routing found on Honda GX-series engines and many popular clones.

Which engines and machines will this muffler kit fit?

This kit fits original Honda GX340, GX390 and GX420 engines and many clone or OEM equivalents such as Harbor Freight Predator 420cc and other 337–440cc engines. It is commonly used on equipment where these engines are installed.

• Compatible with Honda GX340, GX390, GX420 series engines and GX clone units
• Works with Harbor Freight Predator 420cc and many 337–440cc engines
• Commonly installed on pressure washers, water pumps, compressors, log splitters and chippers

What parts are included and what does each do?

The kit arrives ready for direct replacement: a muffler housing, exhaust pipe/manifold, two gaskets, studs and nuts plus a spark plug. These parts restore the exhaust path and seal between engine head and muffler while providing the mounting hardware required for installation.

• Muffler assembly: replaces the aging muffler body and heat shield
• Exhaust pipe/manifold: routes exhaust from cylinder head to muffler
• Two gaskets and studs/nuts: ensure a tight, leak-free seal and secure mounting
• Spark plug (included): convenience for routine maintenance during replacement

How difficult is installation and what tools will I need?

Installation is straightforward for anyone comfortable with basic engine maintenance. You’ll remove the old muffler and manifold, fit the new gaskets and align the assembly to the cylinder head, then secure the provided studs and nuts. No welding or complex modification is required if the engine is the compatible pattern.

• Basic hand tools: ratchet, sockets, box wrenches and screwdrivers
• Torque wrench recommended to tighten nuts to manufacturer specs
• Allow 30–60 minutes for a single-unit replacement depending on access

Will this replace OEM part numbers and work with other brand equipment?

The HZ kit is produced to match the mounting and dimensions of several OEM Honda part numbers and a broad list of aftermarket equipment models. It’s a cost-effective substitute for worn OEM mufflers on many branded machines that use GX-style horizontal engines.

• Designed as a replacement for common Honda GX muffler and manifold part numbers
• Used successfully on units from Simpson, DeWalt, Powermate, NorthStar and others
• Compatible with many clone engines from Loncin, Lifan, Duromax, Generac and more

Who this is for: Mechanics, DIYers and rental shops that service small engine equipment and need a single kit to restore exhaust performance and reduce leaks or excessive noise. It’s suited for anyone maintaining pressure washers, pumps, compressors, chippers or other machinery powered by Honda GX-series engines or compatible clones who prefer a full replacement kit with all required hardware included.