Keihin Carburetor: History, Models & Identification Guide

History

Keihin Corporation was founded in 1956 as a carburetor manufacturer, later becoming a key supplier to Honda Motor Company. Over decades, Keihin expanded from simple slide carburetors to sophisticated constant-velocity (CV) designs used in Honda road bikes and racing engines. In 2020, Honda merged Keihin, Showa, Nissin, and Keihin into a unified company called Hitachi Astemo.

Key Carburetor Series

PB / PW Series (Small Displacement) The PB18 and PW20 are single-slide carburetors found on Honda CG125, CD70, and similar commuter bikes. Their simple design makes them reliable and easy to rebuild.

CV / VB / VA Series (Road Bikes) Constant-velocity carburetors used on Honda CB250 through CB750. The VB23A on the Honda CB400 and the VA21 on older CB750 models are popular rebuild targets.

PE / PD Series (Off-Road) The PE22 and PE28 are slide carburetors designed for the Honda XR and CRF off-road series, offering responsive throttle for trail riding.

FCR Series (Race-Derived) Flat-slide racing carburetors fitted to Honda CBR600 and CRF450 competition models. High-performance with extensive jetting options.

Identification

Keihin carburetors are identified by a casting code on the carburetor body (e.g., "PB18A", "VB23A"). Cross-reference this code with your year and model specification to confirm correct rebuild kit compatibility.

Aftermarket Rebuild Kits

CarbForge compatible rebuild kits for Keihin carburetors include:

• Main jet, pilot jet, needle jet
• Float and needle valve assembly
• Diaphragm (for CV types)
• All gaskets and O-rings
• Pilot air screw with spring