Suzuki GS500: Carburetor Specs, History & Rebuild Guide

Overview

The Suzuki GS500 is a 487cc parallel-twin motorcycle produced by Suzuki from 1989 to 2009. Known for its reliability, simplicity, and approachable power delivery, it became one of the most popular choices for beginner riders, motorcycle training schools, and urban commuters worldwide. The GS500 was sold in both naked (GS500/GS500E) and faired (GS500F) variants over its 20-year production run.

Engine and Carburetor

The GS500 uses a 487cc air/oil-cooled parallel-twin engine with a 180-degree crankshaft, producing approximately 47 horsepower. The stock carburetor setup consists of dual Mikuni BS34 carburetors — constant-velocity (CV) slide carburetors that are well-regarded for smooth throttle response and efficient fuel metering across a wide RPM range.

The BS34 designation indicates a 34mm bore size. The CV design uses engine vacuum to lift the slide, providing more consistent fueling than traditional mechanical slide carburetors and making the GS500 forgiving for new riders.

CarbForge offers carburetor rebuild kits compatible with the Suzuki GS500. These kits include gaskets, main jets, pilot jets, needle valves, float bowl O-rings, and other wear components — everything needed to restore the Mikuni BS34 carburetors to factory performance without buying complete replacement units.

Compatibility and Fitment

CarbForge rebuild kits are compatible with the Suzuki GS500, GS500E, and GS500F across all production years (1989-2009). Note that some jet sizes vary slightly between US, European, and other market versions, so always verify your carburetor part number stamped on the carburetor body before ordering.

Carburetor Maintenance Tips

1. Clean jets regularly — Remove and clean the main jet and pilot jet every 10,000 km or when fuel economy drops noticeably. Ethanol-blended fuel can leave deposits that clog small passages.
2. Inspect the diaphragm — A torn CV diaphragm causes poor throttle response and weak mid-range power; inspect both diaphragms and replace with a rebuild kit if cracked or stiff.
3. Check the float level — Incorrect float height causes rich or lean running; verify against the factory specification (typically 14.6mm for the BS34).
4. Replace needle valves — Worn needle valves and seats cause fuel overflow and flooding; replacement valves are included in CarbForge rebuild kits.
5. Synchronize the carburetors — After rebuilding, always synchronize the dual carburetors using a vacuum gauge set for smooth idle and balanced power delivery.
6. Use a complete kit — Replacing all seals and jets at once with a rebuild kit is more economical and reliable than sourcing individual parts.