The Mikuni BS26 carburetor is a vacuum-controlled, slide-type carburetor designed for use on motorcycles, ATVs, and small engines. It features a 26mm throttle bore and is capable of delivering a wide range of fuel flow rates to suit various engine applications.
Disconnect the throttle cable, choke cable (or enricher wire), fuel line, and vacuum lines. Loosen the intake boot clamps and pull the carburetor free.
Before you begin, ensure you have a clean, well-lit workspace. A digital camera is an invaluable tool—take clear, detailed photos at every step of disassembly to ensure correct reassembly. Work on a large, clean mat to prevent losing small components like springs, washers, and tiny O-rings. mikuni bs26 carburetor manual verified
Before making modifications, baseline your carburetor using the verified factory specifications. While specific jetting varies slightly by vehicle manufacturer (such as Suzuki or Yamaha), standard baseline values provide a reliable starting point. Factory Specification / Measurement Main Jet (Stock) #110 to #132.5 (Application dependent) Pilot Jet (Stock) #15 to #22.5 Pilot Air Screw 1.5 to 2.25 turns out from lightly seated Float Height 17.1 mm ± 1.0 mm (Measured from gasket surface) Fuel Level 4.0 mm ± 0.5 mm below the bowl mating surface Idle Speed 1,300 – 1,500 RPM (Typical engine baseline) 2. Component Diagram and Anatomy
Use JIS (Japanese Industrial Standard) Phillips screwdrivers to avoid stripping the soft brass or aluminum screws common on these units. Step-by-Step Tuning Order Loosen the intake boot clamps and pull the carburetor free
The BS26 is a precision instrument, and cleanliness is its best friend. The following steps are collated from official guides and verified manual procedures.
A thick brass or plastic T-fitting located between the carburetor body (if dual) or on the side. Connects directly to the fuel tank petcock line. Work on a large, clean mat to prevent
Look inside the plastic slide. Use needle-nose pliers or a small socket to compress and remove the plastic retainer clip. Tip the slide upside down to drop out the jet needle, e-clip, and tiny plastic washers. Note the exact order of these washers for reassembly. 3. Float Bowl and Jet Removal
