Located next to the main jet inside a recessed well. It manages fuel delivery from idle up to 1/4 throttle. 3. The Float Chamber Assembly
The BS26 is a constant-velocity carburetor, meaning the slide position is not mechanically linked to the throttle grip. Instead, a vacuum port downstream of the throttle valve lifts the diaphragm slide against spring pressure.
Once installed, use these diagnostic procedures to dial in performance. Pilot Circuit Tuning (Idle to 1/4 Throttle) Warm the engine to operating temperature.
Complete Mikuni BS26 Carburetor Service Manual The Mikuni BS26 is a constant velocity (CV) carburetor widely used in small-displacement motorcycles, ATVs, and scooters. This verified service manual provides comprehensive instructions for identification, teardown, cleaning, inspection, and tuning. 1. Technical Specifications and Identification mikuni bs26 carburetor manual verified
Essential for preventing overflow or fuel starvation. Measurement is typically taken from the gasket surface to the highest point of the float.
These settings are for a stock, unmodified engine at sea level.
[ Top Cap / Vacuum Cover ] || [ Return Spring ] || [ Vacuum Diaphragm & Slide ] || [ Jet Needle ] || ========= Carb Body ========= [ Intake ] [ Engine ] ============================= || [ Pilot / Main Jets ] || [ Float & Needle Valve ] || [ Float Bowl ] Key Sub-systems Located next to the main jet inside a recessed well
Secures the vacuum chamber with two or three screws. Return Spring: Pushes the slide down when vacuum drops.
Back the screw out counter-clockwise as a baseline setting. Warm the engine up to operating temperature.
Ensure there are no tears or pinholes in the black rubber diaphragm. A tear prevents the slide from lifting. The Float Chamber Assembly The BS26 is a
: Engine overheats, backfires, or requires choke even when warm; spark plugs look white.
Locate the screw on the bottom or side of the body. If blocked by a metal EPA anti-tamper plug, drill a tiny hole into the plug, insert a sheet metal screw, and pull the plug out. Count the exact number of half-turns it takes to gently seat the screw before removing it completely. Remove the screw, spring, tiny washer, and rubber O-ring. 4. Cleaning and Inspection Protocol
