Mikuni Bs26 Carburetor Manual Verified 2021 -

Sits inside the slide, tapering down into the main jet emulsion tube. The Carburetor Body Air Pilot Screw: Controls the idle fuel-air mixture.

The Mikuni BS26 carburetor is a reliable and efficient component, and with the guidance in this verified manual, you can confidently service and tune it for peak performance. Understanding its vacuum-operated design, methodically cleaning each component, and adjusting the three main circuits in order are the keys to success.

Use a precise flathead screwdriver to remove the main jet, pilot jet, and main jet emulsion tube. 2. Cleaning and Chemical Treatment mikuni bs26 carburetor manual verified

Inspect the diaphragm rubber for splits. Ensure the slide moves up and down freely inside the bore without binding. Issue 2: Fuel Leaks From Overflow Tubes or Airbox

Locate the fuel mixture screw on the side or bottom of the body. Gently turn it clockwise until it lightly seats, counting the exact number of half-turns. Write this number down. Back the screw completely out. Use a dental pick to retrieve the spring, small metal washer, and rubber O-ring hidden inside the passage. Cleaning and Inspection Protocol Do not submerge rubber parts in harsh solvents. Sits inside the slide, tapering down into the

Before making modifications, establish your baseline. While exact jetting varies by vehicle manufacturer (such as Yamaha, Suzuki, or Kawasaki), the standard Mikuni BS26 baseline configurations are detailed below. Standard Factory Specification Main Jet (Large Round) #110 to #132.5 (Application dependent) Pilot Jet (Idle Jet) #15 to #22.5 Needle Jet P-0 or P-2 Series Jet Needle 4D13 or 5E26 Float Height 21.4 mm ± 1.0 mm (Measured from gasket surface) Pilot Screw (Fuel Screw) 1.5 to 2.5 turns out from lightly seated How the Mikuni BS26 Works

Issue 3: Hanging Idle (Engine Stays at High RPM After Letting Go of Throttle) Cleaning and Chemical Treatment Inspect the diaphragm rubber

Governs the fuel-air mixture at wide-open throttle.

#95 to #110 (Varies by vehicle manufacturer) Pilot Jet (Stock standard): #15 to #22.5

Use compressed air to blow out all internal circuits and dry the parts completely. 5. Critical Reassembly and Float Level Verification The Verified Float Height Measurement

| Symptom | Probable cause | Manual verification step | |---------|----------------|---------------------------| | Hesitation at 5000 rpm | Torn diaphragm | Visual inspection; blow lightly into vacuum port—slide must rise smoothly | | Hard start cold | Clogged starter circuit | Remove starter plunger; check tiny fuel passages with carb cleaner | | Rich idle (black plugs) | Pilot screw too far in | Reset to 2.5 turns out; replace pilot jet if >3.5 turns required | | Surge at steady throttle | Incorrect float height | Remeasure at 30° angle; adjust tang gently | | High idle (1800+ rpm) | Vacuum leak or stuck slide | Spray propane around intake boots; check slide for free movement |