Butom C1M-EL37B Carburetor for Husqvarna 445/450 Series | 506450401

Overview

The Butom C1M-EL37B carburetor kit is designed to replace aging parts on select Husqvarna chainsaws and compatible models. This all-in-one solution combines a ready-to-install carburetor with essential accessories, aiming to restore steady idle, predictable throttle response, and reliable starts. While it offers the feel of a near-original setup, results will vary with proper installation and maintenance. The kit emphasizes practical, real-world performance and ease of use for everyday tasks around the shed, yard, or job site.

Compatibility and replacement details

This carburetor replaces C1M-EL37B and 506450401 and is used on Husqvarna 445 and 450 family models, including 445, 445E, 445II, 450, 450E, and 450II. It also lists compatibility with Jonsered CS2245 S II, CS2250 S II, McCulloch CS450, and Craftsman 358382000 chainsaws, making it a versatile option for users with mixed toolsets.

Key specs you may reference during fitment checks include mounting hole distance (center to center) of 31 mm, throttle diameter of 13.9 mm, choke diameter of 19 mm, venturi diameter of 11 mm, fuel inlet line size of 3 mm, and primer bulb line size of 3 mm. These details reflect the kit’s intent to align with common Husqvarna and related models while providing a cohesive substitution path when service parts are scarce.

What’s included in the kit

• Butom 506450401 carburetor x1
• Air filter x1
• Primer pump x1
• Spark plug x1
• Fuel filter x1
• Fuel line x2

Key features and performance

• All-in-one tune up kit saves time and money by providing essential parts in a single package.
• Factory-tuned and ready to install for convenient setup and reduced guesswork.
• Wet flow tested to emulate real-world engine operation and improve consistency.
• Premium materials include brass components, composite rubber diaphragms, and an anodized aluminum body to resist heat and wear.

In real-world use, you may notice smoother throttle response, steadier starts, and more predictable fueling behavior as components work in concert. The kit’s all-in-one design helps streamline maintenance workflows and minimizes the need for separate purchases, which can be a practical safeguard for busy users and service professionals alike.

Installation and expectations

Expect a straightforward install with components designed to match the original fitment. While the kit is pre-tuned for convenience, proper installation, calibration, and routine care will influence long-term performance. For best results, replace worn gaskets and seals as part of a comprehensive tune-up routine.