#110 / #112.5 (Varies by region and emissions) Pilot Jet (Idle): #17.5 or #20 Pilot Screw Factory Setting: 2.0 to 2.5 turns out Float Height: 13mm to 14mm ( ±plus or minus
When these carburetors sit with modern ethanol fuels, the tiny internal passages clog easily. This comprehensive service manual provides step-by-step instructions to strip, clean, rebuild, and tune your Mikuni BDS26 to restore factory performance. Technical Specifications & Factory Defaults
These procedures have been refined by the community and are drawn directly from factory procedures and enthusiast experience.
Crucial for removing bowl screws without stripping them.
The threads strip easily. Spec is 2.5 Nm (22 in-lb) – use a small torque wrench.
Once the Mikuni BDS26 is reinstalled on the engine, you may need to perform fine-tuning adjustments. Probable Cause Corrective Action Lean pilot circuit / Torn coasting enricher diaphragm Check enricher valve; turn pilot screw out 1/4 turn. Engine bogs at 4,000+ RPM Torn vacuum slide diaphragm / Clogged main jet Inspect slide action; clear main jet passage. Fuel leaks from overflow tubes
Flip the carbs over and remove the four screws holding the float bowls. If they are stuck, a light tap with a plastic mallet can help.
You will most commonly find the BDS26 on:
Manages fuel at closed to 1/4 throttle. This includes the pilot jet and the pilot screw (often hidden behind a brass plug).
Lift the plastic float assembly straight up, catching the float needle valve (needle seat plunger) attached to the float tang.
Spray soapy water on intake boots to check for bubbles; adjust cable play.
Reassembly follows the reverse order of disassembly, with critical calibration steps required along the way.
If the measurement is outside the window, carefully bend the small metal tang on the float arm using needle-nose pliers. Re-measure. 2. Pilot Mixture Bench Setup
Carefully lift the cover. Be mindful of the long spring underneath; it will try to push the cap away.
