Ruma Muffler Kit for Honda GX340 GX390 GX420 - Complete Replacement

In this review the Ruma Muffler Kit is evaluated as a direct replacement for Honda GX340, GX390 and GX420 small engines. The kit is aimed at owners of pressure washers, water pumps, snowblowers, log splitters and other equipment that use 11hp to 16hp Honda OHV style engines and clone equivalents. The single biggest reason to buy is convenience: the kit arrives with the muffler assembly, exhaust pipe/manifold, gaskets, mounting hardware and even a spark plug so a full muffler rebuild or repair can be completed without hunting parts.

Key Features

• Complete muffler assembly: Replaces GX390 and GX340 exhaust mufflers so you can restore proper exhaust routing and noise control with one part.
• Included exhaust pipe and manifold: The exhaust pipe and manifold are provided to match common small engine layouts and reduce fitment headaches during installation.
• Gaskets and mounting hardware: Two gaskets, two mounting studs and five nuts are included so the kit is ready for installation without extra trips to the hardware store.
• Fits many engines and equipment: Compatible with Honda GX340, GX390, GX420 and many clone engines used in pressure washers, pumps, snowblowers and log splitters for broad applicability.
• Spare spark plug included: A spare spark plug in the package supports basic maintenance while replacing the muffler assembly.

Who It's For

This kit is for DIYers and small engine technicians who need a straightforward replacement for worn or damaged muffler assemblies on Honda GX340, GX390 and GX420 engines or compatible clones. It especially suits owners of pressure washers, water pumps and various outdoor power equipment who want a complete set of parts for a single repair session.

Those who should look elsewhere are owners of factory generator models or engines with unique muffler geometries not listed in the compatibility notes, or users who require OEM-branded parts for warranty or original-equipment certification.

Pros & Cons

Pros

• Fits a wide range of 11hp to 16hp Honda and clone engines, making it versatile for many tools and machines.
• Comes as a full rebuild kit with gaskets, studs, nuts and an exhaust pipe so installation is efficient.
• Customers report solid build quality and easy installation, reducing downtime for repairs.

Cons

• Bolt strength has mixed feedback, so some users may prefer to replace mounting hardware depending on use conditions.

Specifications

Product type	Muffler replacement kit
Compatible engines	Honda GX340, GX390, GX420 and compatible clone engines (11hp-16hp)
Includes	Muffler assembly, exhaust pipe/manifold, 2 gaskets, 2 mounting studs, 5 nuts, 1 spark plug
Replaces	OEM muffler assemblies and covers including part numbers similar to 18310-ZE2-W61 and 18320-Z5T-010
Intended equipment	Pressure washers, water pumps, snowblowers, log splitters, chipper shredders, air compressors (not generators)
Brand	Ruma

Our Verdict

The Ruma Muffler Kit is a practical, cost-effective solution for owners of Honda GX340/GX390/GX420 and compatible clone engines who need a quick, complete replacement. It delivers good fit and function for pressure washers, pumps and other outdoor equipment, and the included gaskets and hardware make installation straightforward. For those needing OEM-labeled parts or heavy-duty mounting hardware, a supplemental parts check is recommended, but for most repair jobs this kit offers strong value.

Frequently Asked Questions

Will this fit my GX390 pressure washer?
It is designed to fit GX390 engines and is commonly used on many pressure washer models that use that engine family.

Are replacement gaskets and nuts included?
Yes, the kit includes two gaskets, two mounting studs and five nuts so it is ready for installation.

Does this work with Harbor Freight Predator 420cc engines?
Yes, the kit lists compatibility with many 420cc clone engines including common Predator 420cc models.