Verified - Mikuni Bs26 Carburetor Manual

Mikuni BS26

The is a Constant Velocity (CV) carburetor widely used on 125cc to 150cc motorcycles and ATVs, such as the Suzuki GN125 and GS125.

• Use an industry carb cleaner or ultrasonic cleaner with mild detergent for jets and small parts.
• Ultrasonic cleaning is highly effective for removing varnish in pilot passages; follow with compressed air and solvent rinse.
• Blow through all drillings from both directions; verify jet orifice sizes with a jet gauge if uncertain.

If you are rebuilding the carburetor, familiarize yourself with the parts layout: mikuni bs26 carburetor manual verified

1. Remove carburetor from bike: drain fuel, disconnect fuel line, throttle, choke, and vacuum hoses; remove mounting clamps.
2. Note and photograph linkage, cable routing, and vacuum connections.
3. Remove float bowl screws; unscrew bowl carefully to avoid gasket damage; drain remaining fuel.
4. Remove float pin, lift float and float valve; inspect seat and valve tip for wear or deformation.
5. Remove pilot screw and spring (if present); remove pilot jet and main jet using proper jet drivers.
6. Remove needle clip and slide assembly: release throttle backplate, withdraw slide and needle.
7. Open vacuum chamber (if diaphragm-type): remove diaphragm cover screws, lift diaphragm ring and diaphragm; inspect for tears or stiffening.
8. Inspect all passageways; use compressed air and carb-safe solvent to clear blockages. Never use excessive wire probes that change bore geometry.
9. Check throttle shaft and slide for scoring; check float bowl for corrosion or varnish.
10. Replace all worn gaskets, O-rings, needle, float valve, and diaphragm as needed.

The Mikuni BS26 carburetor is a vacuum-operated, slide-type carburetor designed to provide optimal performance and fuel efficiency. It features a 26mm throttle bore and is typically used on single-cylinder engines. The BS26 carburetor is known for its simplicity, ease of use, and adjustability. Mikuni BS26 The is a Constant Velocity (CV)

• Verified alternate method: Use a length of clear tubing filled with 2-stroke oil on the right carb's vacuum port, or use a "manometer stick." Sync spec: Within 10mmHg at idle.

1. Poor engine performance: Check for clogged jets, incorrect jetting, or dirty air filter.
2. Difficulty starting: Check for faulty choke operation, clogged pilot jet, or incorrect idle mixture adjustment.
3. Hesitation or bogging: Check for clogged main jet, incorrect main jet selection, or dirty air filter.

| Modification | Required change | Jet size change | |--------------|----------------|------------------| | Pod filter (no airbox) | Impossible to tune well – BS26 needs airbox restriction | +2 on main jet, raise needle 1 clip, pilot +2 sizes – but still runs poorly | | High-flow exhaust | Usually none | Only if popping on decel → +1 on pilot jet | | High altitude (>2,000m) | Drop main jet by 1 size per 1,000m | Example: #100 → #95 | Use an industry carb cleaner or ultrasonic cleaner