Mikuni Bs26 Carburetor Manual | Verified

Note: Values are for sea level (0–1,000m), 20°C ambient. Adjust for altitude/weather.

| Component | Suzuki GSX250 | Kawasaki ZZR250 | Bajaj Pulsar 220 | |-----------|---------------|-----------------|------------------| | Main Jet | #97.5 | #102 | #115 | | Pilot Jet | #35 | #38 | #40 | | Jet Needle | 5D28 (clip 3rd) | 5C30 (clip 2nd) | 6F24 (clip 3rd) | | Needle Jet | P-2 (O-2) | P-4 (O-4) | P-6 | | Pilot Screw (turns out) | 1.5 – 2.0 | 2.0 – 2.5 | 2.0 | | Float height (mm) | 13.0 ± 1 | 14.5 ± 1 | 12.8 ± 1 | mikuni bs26 carburetor manual verified

Verified check: Mikuni genuine jets are stamped with a square symbol. Aftermarket "Mikuni-style" jets often vary by 5-10% – always use genuine Keihin or Mikuni. Note: Values are for sea level (0–1,000m), 20°C ambient

| Parameter | Spec | |-----------|------| | Type | Constant Velocity (CV), downdraft | | Bore size | 26 mm | | Venturi diameter | 24.5 mm (effective) | | Fuel inlet | 5/16" (8mm) barb | | Float bowl gasket | Rubber (O-ring type) | | Pilot air jet | 120–130 (varies by model) | | Main air jet | 180–200 | | Idle speed | 1,200–1,300 RPM | Verified check : Mikuni genuine jets are stamped

Many online guides incorrectly suggest inverting the carburetor fully. The factory manual specifies a 30° angle (float tang just touching the needle spring tip, not compressing it). Full inversion compresses the spring and gives a false reading (~11 mm vs correct 13 mm), causing a lean condition.

You do not need a new carburetor. You need a diagnostic flowchart.

| Symptom | Common Forum Advice | Verified Manual Fix | | :--- | :--- | :--- | | Hesitation at 1/4 throttle | "Turn the PAS to 4 turns." | Wrong. Replace the pilot jet (#40) and set PAS to 2.5 turns. 4 turns means the pilot jet is clogged. | | Backfire on decel | "You have a header leak." | Check the mixture screw O-ring. If it is flat or missing, you have an unmetered air leak. Replace the O-ring (Part # 13373-43580). | | Slide won't rise | "Buy a stronger spring." | Check the diaphragm vent hole. On the air filter side of the carb, there is a tiny 1mm passage. If clogged, the slide cannot sense vacuum. Blow it out with compressed air. | | Rich idle, black smoke | "Lower the needle clip." | Check the float needle seat. The BS26 has a removable seat with a built-in filter screen. If the screen is torn, debris holds the needle open. Inspect with a bright light. |