Bds26 Service Manual | Mikuni

They are handed due to the offset needle jet. Reverse installation causes the needle to bind.

  • Push the needle out from the bottom of the slide to remove it. Note the clip position (count grooves from the top).

    • If you’d like, I can:

    For those servicing the Mikuni BDS26 (a double-carburetor setup often found on models like the Hyosung GV250), a critical feature within official service documentation is the Detailed Component Specification Table

    . This data is vital because the BDS26 uses slightly different settings for the front and rear carburetors to account for engine heat and airflow variations Key Technical Specifications (GV250 Standard) Carburetor Type MIKUNI BDS 26 (Double) Main Jet (M.J.) : Front 90 / Rear 87.5 Jet Needle (J.N.) : 2nd clip position for both : 1,450 – 1,550 rpm Float Height Pilot Jet (P.J.) Maintenance & Service Tips Ultrasonic Cleaning

    : For heavily gummed-up carburetors, professional-grade ultrasonic cleaners are often recommended. However, you must remove all rubber and plastic parts

    (diaphragms, O-rings, and floats) before soaking, as cleaning solvents can cause them to swell or degrade XJRider.com Throttle Shaft Seals

    : If your engine has a hanging idle or runs lean despite proper jetting, the throttle shaft seals may be leaking air. Specialized guides like the LiteTek Rebuild Guide

    offer instructions on replacing these often-overlooked seals LiteTek.co JIS Screwdrivers : To avoid stripping the soft brass screws, use Japanese Industrial Standard (JIS) screwdrivers rather than standard Phillips-head tools Synchronization

    : Because it is a dual-carb setup, you must synchronize the throttle plates after any major service to ensure both cylinders are pulling equal vacuum For complete visual walkthroughs, you can find a Mikuni BDS26 Cleaning & Overhaul guide or full technical breakdowns in the ATKUSA Fuel System Manual specific adjustment steps for setting the float height or synchronizing the idle? Fuel System | ATKUSA

    Connect the fuel hoses 3, 4 securely. Disconnect the fuel hose 4, and check the fuel. MIKUNI BDS 26 TYPE (DOUBLE) Fuel System | ATKUSA

    Float height. Throttle cable play. rpm. 17. 0.5~1.0. Needle jet (N.J.) Pilot jet (P.J) Throttle value. By pass (B.P.) Valve seat ( Mikuni BDS26 Carburetor Specifications | PDF - Scribd

    You're looking for the service manual for the Mikuni BDS26 carburetor!

    The Mikuni BDS26 is a popular carburetor used on various motorcycles, ATVs, and other small engines. While I couldn't find a single, definitive source for the service manual, I can provide you with some options to help you obtain the manual or repair information:

    Official Sources:

    Third-Party Sources:

  • Repair Manuals and Guides:

    • DIY Tips and Tricks:

    If you're unable to find a service manual, you can try searching for specific repair guides or tutorials on YouTube or other online resources. Additionally, you can consult with a small engine mechanic or a motorcycle repair expert familiar with Mikuni carburetors.

    Keep in mind that working on carburetors requires expertise and patience. Make sure you follow proper safety procedures and take your time when repairing or tuning your Mikuni BDS26 carburetor.

    The Mikuni BDS26 is a constant-velocity (CV), "double" carburetor system commonly found on motorcycles such as the Yamaha XJ600 Seca II , Yamaha SRV250 Renaissa , and Hyosung GV250

    . Understanding its service requirements is essential for maintaining smooth throttle response and engine reliability. 1. Key Specifications & Components

    The BDS26 features a 26mm bore and relies on a vacuum-operated diaphragm to lift the slide, ensuring consistent air velocity.

    Main Jet: Standard sizes range from #87.5 to #90 depending on the cylinder (front/rear). Pilot Jet: Typically #20.

    Float Height: Essential for preventing fuel overflow; for the Seca II, the dry factory specification is 6.2mm to 8.2mm. Idle RPM: Generally set between 1,450 and 1,550 RPM. 2. Routine Maintenance & Cleaning

    Over time, modern ethanol-blended fuels can leave deposits that clog the small orifices of the BDS26. Mikuni BDS26 Carburetor Specifications | PDF - Scribd

    Mikuni BDS26 is a 26mm dual carburetor commonly found on motorcycles like the Yamaha XJ600 (Seca II) and the Hyosung GV250. While a single standalone manual for only the BDS26 is rare, its service procedures are detailed within the factory service manuals (FSM) for these specific bikes. Core Specifications Idle Speed: 1,450 – 1,550 RPM. Float Height (Dry Method): 6.2mm to 8.2mm (0.24" to 0.32"). Fuel Pressure: Requires 4 psi or less.

    Main Components: Uses a vacuum-operated diaphragm, jet needles (J.N.), and needle jets (N.J.), which are prone to wear over time. Service & Maintenance Procedures

    Disassembly: Remove the fuel tank and disconnect throttle/choke cables. Access the internal components by removing the diaphragm cover and float chamber body. mikuni bds26 service manual

    Cleaning: Use compressed air and carburetor cleaner to clear all jets and passages of varnish or deposits.

    Float Adjustment: Measure the height from the gasket surface to the top of the float while the arm just touches the needle valve without compressing the spring.

    Air/Fuel Mixture: Turning the air screw clockwise decreases air (richer mixture), while counterclockwise increases air (leaner mixture). Troubleshooting Common Issues

    Fuel Leaks: Often caused by worn gaskets or a failing needle valve seat.

    Poor Idle/Starting: Usually due to clogged pilot jets or improperly adjusted idle mixture screws.

    Bogging at High RPM: May indicate a torn vacuum diaphragm or incorrectly sized main jets.

    Detailed guides and diagrams for rebuilding these carburetors can be found at ATKUSA or through technical community posts on XJRider. If you'd like, I can:

    Find the exact jet sizes for your specific motorcycle model. Provide a step-by-step cleaning guide using standard tools.

    Search for OEM-equivalent rebuild kits and where to buy them. Which of these would be most helpful for your project? AI responses may include mistakes. Learn more Fuel System | ATKUSA

    The Mikuni BDS26 is a constant-velocity (CV) downdraft carburetor commonly used on V-twin motorcycles, most notably the Yamaha XV250 Virago (and its V-Star 250 successor) and the Hyosung GV250. While there is no single standalone "service manual" authored solely by Mikuni for this specific model, comprehensive maintenance data is found within the vehicle-specific service manuals for these motorcycles. Technical Specifications

    For accurate tuning and rebuilds, follow these standard factory specifications for the : Bore Size: 26mm Idle Speed: 1,450 – 1,550 RPM Float Height: 17.0mm

    Main Jet (M.J.): #90 (Front), #87.5 (Rear) — Note: Jets may differ between front and rear cylinders. Pilot Jet (P.J.): #20 Jet Needle (J.N.): 2nd clip position (Standard)

    Air Screw Setting: Approximately 1.5 to 1.75 turns out from lightly seated. Service Resources & Documentation They are handed due to the offset needle jet

    Yamaha XV250 Service Manual: This is the most complete source for the BDS26. You can find free PDF versions on community sites like the Virago 250 Street Manual or detailed digital guides at Cyclepedia.

    Hyosung GV250 Fuel System Manual: Provides exploded diagrams and specific jetting for the BDS26 double carburetor setup, available through ATKUSA

    General Mikuni Tuning: For theory on how the pilot circuit, needle jet, and main jet interact, refer to the Mikuni VM Tuning Manual

    , which covers the universal principles applicable to most Mikuni carbs. Maintenance Tips Mikuni BDS26 Carburetor Specifications | PDF - Scribd

    The Mikuni BDS26 is a 26mm dual constant velocity (CV) carburetor commonly found on motorcycles like the Yamaha Virago XV250 (V-Star 250) and Hyosung GV250 . 1. Technical Specifications

    The following specifications are standard for the Mikuni BDS26 used on 250cc V-twin applications: Specification Bore Size Idle Speed 1,450 – 1,550 RPM Float Height Main Jet (Front/Rear) Main Air Jet Pilot Jet Jet Needle 2nd groove Throttle Cable Play 0.5 – 1.0mm 2. Essential Maintenance & Cleaning

    Safety First: Gasoline is explosive; work in a well-ventilated area away from sparks.

    Tools: Use a high-quality JIS #2 screwdriver for the float bowl screws to prevent stripping.

    Deep Cleaning: For heavy buildup, remove the carburetor and disassemble key components like the float, jets, and needle valve.

    Ultrasonic Cleaning: A mixture of 1 part degreaser (like Simple Green Pro HD) to 3 parts water is highly effective for clearing internal varnish.

    Jet Maintenance: Clear the pilot and main jets with compressed air. Do not use wire to poke through jets as it can damage the precise orifice. 3. Tuning & Adjustments Fuel System | ATKUSA

    This controls your fuel level.