Spray aerosol carb cleaner directly into every single orifice, pilot circuit hole, and air bleed jet. Verify that fluid sprays out cleanly from the corresponding exit holes inside the venturi throat.
Remove every o-ring, gasket, and diaphragm. Carb cleaner will instantly warp, dissolve, or ruin rubber components.
Work in a highly ventilated space, away from pilot lights, water heaters, or sparks.
Carefully pull the rubber vacuum diaphragm and slide assembly straight up out of the carburetor body.
: Factory manuals are available for purchase from dealerships or online retailers. Alternatively, a Haynes manual for your motorcycle can be a more affordable and user-friendly alternative, as it compiles service procedures for all systems, including the carburetor. mikuni bds26 service manual
Check the needle valve tip. If it has a visible ring or groove, it won’t seal properly, leading to a leaking carb.
Locate the float retaining pin. Use a small punch to slide it out.
If you would like to troubleshoot a specific issue with your Mikuni BDS26, tell me (such as hanging idle, bogging, or leaking fuel), or share your current jetting sizes . I can help you pinpoint the root cause or calculate a custom setup. Share public link
Japanese Industrial Standard (JIS) bits prevent stripping the soft brass jets and bowl screws. Carburetor Cleaner: Aerosol spray with a straw attachment. Compressed Air: For blowing out cleared passages. Spray aerosol carb cleaner directly into every single
Working with carburetors exposes you to volatile fuel and delicate, precision-machined brass components. Required Tools
To finalize your tune, synchronize the carburetors using a vacuum gauge tool if yours is a dual-carburetor linked setup. Adjust the synchronization screw between the linkages until both cylinders pull identical vacuum readings at a warm idle.
: Automotive forums for your specific model are excellent resources. Owners often share links to official manuals. For example, XJRider.com is a fantastic source for Seca II/XJ600 information, containing detailed guides that directly reference the FSM for procedures like float height setting.
Inspect the rubber diaphragm for pinholes, tears, or stiffness by holding it up to a bright light. Carb cleaner will instantly warp, dissolve, or ruin
Standard factory settings can vary slightly by motorcycle model, but the following are common baseline values: Standard Specification Float Height (Dry) 6.2 mm – 8.2 mm (often set to for balance) Main Jet (M.J.) #90 (Front), #87.5 (Rear) for some models Pilot Jet (P.J.) 1,450 – 1,550 rpm Pilot Screw 2.5 turns out from lightly seated Step-by-Step Rebuild Guide
: Inline-four cylinder bikes use a bank of four BDS26 carbs.
This article serves as a comprehensive guide—a walkthrough—covering essential maintenance, tuning, and rebuilding techniques. 1. Understanding the Mikuni BDS26 Carburetor
The threads strip easily. Spec is 2.5 Nm (22 in-lb) – use a small torque wrench.