Mikuni Bs26 Carburetor Manual Verified

Prior to disassembly, thoroughly clean the exterior of the carburetor with a dedicated carburetor cleaning spray to prevent dirt from entering the internal passages. 1. Top Cover and Diaphragm Removal Remove the two top cover screws.

Mikuni BS26 Carburetor Manual Verified: Complete Tuning & Service Guide

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. mikuni bs26 carburetor manual verified

Dominates throttle positions between 1/4 and 3/4 open. The tapered needle slides inside the needle jet, regulating fuel as engine vacuum lifts the diaphragm assembly.

Turn the pilot screw inward until it lightly seats, then back it out 2 full turns. Prior to disassembly, thoroughly clean the exterior of

| | Likely Cause | Recommended Action | | :--- | :--- | :--- | | Engine won't start | No fuel in float bowl, clogged pilot jet, or faulty choke/enricher | Check for fuel delivery, remove and inspect the pilot jet, and verify the choke/enricher plunger operates freely. | | Runs rich (black smoke, poor fuel economy) | High float level, oversized main jet, or fuel screw open too far | Verify and adjust float height. Test leaner main jet sizes. Turn fuel screw in to lean idle mixture. | | Runs lean (backfiring, hesitation) | Vacuum leak, low float level, undersized main jet, or fuel screw set too lean | Carefully spray starting fluid around the intake manifold to check for air leaks. Adjust float height. Test richer main jet sizes. | | Uneven idle, stalls | Clogged pilot circuit, improper pilot screw adjustment, or vacuum leak | Clean pilot jet and its passageways thoroughly. Re-adjust the pilot screw. Inspect carburetor and intake manifold gaskets. | | Poor acceleration, flat spot | Incorrect needle height setting, clogged main jet, or faulty diaphragm | Move needle clip to richen mixture. Clean or replace main jet. Inspect vacuum slide diaphragm for tears or pinholes. | | Engine revs but has no power | Worn or torn vacuum diaphragm, severely restricted air filter | Remove and carefully inspect the rubber diaphragm. Replace if damaged. Clean or replace the air filter element. |

Remove the four screws securing the float bowl. If the screws are seized, use an impact driver or vice grips to avoid stripping the soft JIS (Japanese Industrial Standard) heads. Mikuni BS26 Carburetor Manual Verified: Complete Tuning &

Mikuni BS26 is a 26mm Constant Velocity (CV) carburetor widely used in small motorcycles and ATVs, such as the Suzuki GN125 or Hyosung GV250. Authentic service procedures and tuning adjustments are critical for maintaining the "variable venturi" effect that allows these units to balance performance with fuel efficiency. Essential Technical Specifications

For a standard Mikuni BS26 setup, technicians typically rely on these verified baseline settings: