Do All Motorcycles Have a Choke?

When it comes to motorcycles, the term 'choke' might ring a bell for those familiar with older models. However, the question 'do all motorcycles have a choke?' is more nuanced than it initially seems. This article explores the history and mechanics of motorcar chokes, their relevance in modern motorcycles, and the reasons behind their gradual decline in contemporary designs.

Understanding the Choke Mechanism

A choke, in the context of motorcycles, traditionally refers to a small brass plate that was placed over the carburetor's air intake when an engine was cold-started. Its primary function was to enrich the fuel mixture, ensuring an adequate supply of fuel to help the engine achieve proper combustion when the air was stale due to the cold. The choke plate effectively blocked some of the incoming air, allowing for a richer fuel-to-air ratio supplied by the carburetor.

Traditional Chokes and Carburetors

During the late 1970s, for instance, constant velocity carburetors were commonly used. These carburetors featured an enrichening circuit that released extra fuel into the system. Additionally, there was often a fast idle circuit used to allow the engine to warm up more rapidly. The term 'choke' was commonly used to describe a mechanism that physically blocked the air intake.

Modern Motorcycle Technology

Fast forward to the present day, the majority of motorcycles now use fuel injection systems, which greatly reduce the need for a traditional choke. In fuel-injected systems, the engine manages the fuel-to-air ratio through sophisticated electronic sensors and control modules, obviating the need for manual enrichment.

For instance, most modern motorcycles, including Harleys, are equipped with fuel injection systems. Even my 2003 Sportster, which has a single carburetor feeding both cylinders, operates using an enrichening circuit designed to compensate for the cold start. The fuel injection systems in contemporary motorcycles ensure that the engine reaches optimal operating conditions quickly and efficiently, often without the need for a choke.

exceptions and Small Engines

While most motorcycle manufacturers have moved away from chokes and carburetors, there are still exceptions, particularly in smaller engines like those used in small lawn mowers and weed wackers. These engines often use a true choke mechanism to achieve the proper fuel-to-air ratio for starting from a cold state. However, even in the realm of Harleys, the use of a true choke plate appears to be a thing of the past. The last Harleys to use carburetors and a true choke were manufactured in 2006, with Sportster models being specifically noted. Since 2007, all new Harley Davidson models have been fuel injected, eliminating the need for a choke.

Conclusion

In summary, the vast majority of modern motorcycles do not have a choke. The advancements in fuel injection technology have made traditional chokes obsolete, providing reliable, efficient, and easy-to-start engines across a wide range of models. However, for those interested in vintage bikes or small engines, understanding the role of a choke and how it operates can provide valuable insights into the evolution of motorcycle technology.

Keywords: motorcycle choke, fuel injection, carburetor, motorcycle engine