Mikuni Bs25 Carburetor Diagram Patched Jun 2026

The Mikuni BS25 is a 25mm round slide carburetor, commonly used in and certain Yamaha or Suzuki small-displacement bikes. Essential Resources & Diagrams

Securely seals the upper vacuum area and holds the slide spring in place.

Remove the carb, take off the top cap, and remove the spring and diaphragm/slide assembly. mikuni bs25 carburetor diagram patched

[0% - 15% Throttle] --> Pilot / Idle Circuit [15% - 25% Throttle] --> Throttle Slide Cutaway [25% - 75% Throttle] --> Jet Needle & Needle Jet [75% - 100% Throttle]--> Main Jet Circuit

[ VACUUM DOME ] <- Vacuum Diaphragm & Return Spring =================== | ___________ | | | | | | <- Vacuum Slide & Jet Needle ---+---|-----v-----|---+--- Air | (Venturi) | Engine <- 25mm Venturi Bore (Intake Side) Flow ===> ===> Flow ---+---|-----------|---+--- | |___________| | <- Needle Jet & Emulsion Tube =================== [ FLOAT CHAMBER ] <- Float Assembly, Needle Valve & Jets The Upper Vacuum Dome The Mikuni BS25 is a 25mm round slide

: When the throttle is wide open, the main jet size acts as the restrictive bottleneck controlling total fuel delivery. Step-by-Step Rebuilding and Maintenance Roadmap BS Carburetors - Mikuni Power

Mikuni BS25 is a Constant Velocity (CV) carburetor commonly used on 150cc engines (like the GY6 150cc) and certain vintage motorcycles. While there is no official "patched" diagram, a "patched" guide typically refers to a visual walkthrough [0% - 15% Throttle] --> Pilot / Idle

Understanding the internal workings via a detailed is the first step to successful restoration. 1. Mikuni BS25 Carburetor Diagram Breakdown

Often found on the side or bottom, used for fine-tuning the idle mixture. Bottom Section (Float Bowl): Float & Needle Valve: Controls the fuel level inside the bowl. Regulates fuel flow at wide-open throttle (WOT). Pilot Jet: Controls fuel flow at idle and low speeds. Float Bowl Gasket: Seals the bowl to the main body to prevent leaks. Visual Reference

Located inside the fuel bowl, this system maintains a constant reservoir of fuel.