The disc at the rear of the carb operated directly by your throttle cable. Pilot (Idle) Screw: mikuni bs25 carburetor diagram patched

Report: Decoding the “Patched” Mikuni BS25 Carburetor – A Field Analysis

1. Introduction

The Mikuni BS25 is a constant vacuum (CV) carburetor commonly found on small-to-medium displacement motorcycles (e.g., Suzuki GN250, Yamaha SR250, early Kawasaki Z250). In workshop parlance, a “patched diagram” refers not to a software patch, but to a manually corrected, annotated, or repaired schematic—often used to overcome design flaws, wear, or tuning issues. The Ultimate Guide to the Mikuni BS25 Carburetor:

Example Parts/Sizes (common helpful references)

• Main jet sizes commonly range 90–115 depending on engine; start matching previous jet or consult engine tuning notes.
• Pilot jets often 15–35 (numbers vary by manufacturer); clean before swapping.
• Needle: standard Mikuni tapered needles with clip positions (V or X series) — match to similar displacement engines.