Mikuni Bs25 Carburetor Diagram Patched -

The Mikuni BS25 is a small, slide-type carburetor commonly found on minibikes, small motorcycles, scooters, and custom builds. “Diagram patched” here means providing a corrected, annotated diagram plus step-by-step guidance for identifying components, common problem areas, and how to safely patch or repair typical faults (jets, floats, fuel leaks, vacuum ports, slide wear). This post gives a practical visual and procedural reference for hobbyists and mechanics.

Mikuni BS25 Carburetor Diagram: Patched & Explained (Full Rebuild Guide)

Have you successfully patched a BS25 diaphragm? (We know you tried). Tell us your horror story in the comments below.

This article provides a comprehensive overview of the BS25, a detailed breakdown of its key components, and how to successfully overhaul (or "patch") it for optimal performance. 1. Understanding the Mikuni BS25 Carburetor Diagram mikuni bs25 carburetor diagram patched

Here's why a "patched" diagram is so critical for the Mikuni BS25:

Use a new float bowl packing/gasket (such as Mikuni TM42/05 for some models). 3. Cleaning Key Passages

A corrected diagram will include a large note next to the TPS: The Mikuni BS25 is a small, slide-type carburetor

Allows you to empty stale fuel from the bottom of the bowl. Common Troubleshooting Scenarios Fuel Leaking from the Overflow

Remove the carb, take off the top cap, and remove the spring and diaphragm/slide assembly.

The tiny O-ring on the mixture screw (air screw) often rots, causing erratic idling. Mikuni BS25 Carburetor Diagram: Patched & Explained (Full

Whether you’re rebuilding a barn-find GN250 or diagnosing a stubborn idle on a 250 Virago, this patched Mikuni BS25 diagram provides the corrected circuit paths that factory manuals often leave ambiguous. Save it to your shop notes.

If you’ve been wrenching on a scooter, dirt bike, or a small ATV (like the Yamaha Vino 125 or early Suzuki Burgman), you’ve likely met the Mikuni BS25. It’s a reliable, constant-depression (CV) carburetor, but it has a dirty little secret:

The small pilot jet passage is narrow and easily clogged by varnished fuel.

Located at the top. The rubber diaphragm must be free of holes or cracks. The Main Jet and Needle: Controls fuel at mid-to-high RPM.