How a Choke Works in Motorcycles
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Something that can often come up for new bike owners is the challenge of starting a bike in cold conditions.
Why is it that starting a motorcycle on a cold winter morning can be a struggle?
Whilst most new bikes have electronic fuel injection (EFI) to help start an engine during colder temperatures, older models (and some new) often don’t have such a luxury. Luckily though, these carburettor engines can combat cold temperatures using a choke valve.
But what exactly is a choke valve or cable and what do bike owners need to know about it?
This article delves into the world of choke valves and cables, helping you understand how this benefits motorbikes.
What is a Choke Valve?
A choke valve/cable is designed to restrict the flow of air in the carburettor of an engine. This helps enrich the fuel-air mixture, improving the ability to start an engine in low temperature conditions.
For carburettor fitted bikes, a choke valve/cable helps ensure there is enough useable fuel to start the engine when temperature and climatic conditions are low. The ratio of air and fuel required to start the engine changes with temperature due to the physics and thermo-dynamics behind combustion and air density.
A cold engine won’t vaporise the fuel as well as it would in warmer conditions, so the choke helps enrich the mixture (either by adding in more fuel or cutting out airflow) to increase the amount of combustible vapour available to start the engine.
Simply put, the choke is about making more fuel available for the engine to use.
On a motorcycle, a choke valve is likely to be a pulling lever either directly attached to the carburettor or indirectly attached to the carburettor via a cable. For any help in finding the right type of cables for any part of your motorbike, don’t hesitate to get in touch with us here at Venhill. Our motorcycle cables are to the highest standard and help enthusiasts and professionals alike, get more out of their bikes.
Each model and make of a motorcycle will utilise choke valves and cables slightly differently. Some motorcycles use a choke to reduce the airflow to enrich the mixture, while others use an enrichment valve that increases the amount of fuel (as opposed to reducing the airflow). Both types achieve the same thing but may be set up differently depending on the model and make of bike.
Once the engine is in use, and naturally warms up, the choke valve can be closed, to reduce additional fuel being used. Keeping the valve open unnecessarily will lead to poor fuel efficiency.
Using a Choke on a Motorcycle
There is no harm using the choke to start an engine. When it’s cold, it can be a necessity to get things going.
Using it unnecessarily will only lead to increase fuel usage but no damage to the vehicle.
Each bike may implement a choke system in its own unique way. This will impact how motorcycle owners go about enriching the mixture in the carburettor.
At some stage, riders will gain an understanding of how long they need to use the choke to get things going. Again, depending on the temperature, this is likely to vary too.
There also isn’t a fixed temperature that would be recommended to start using the choke. Instead, motorcycle owners should simply be aware of the benefit of using the choke. If the bike is struggling to start, this is the first thing to try.
Electronic Fuel Injection
An alternative to carburettors (and something growing in popularity in new bikes) is an electronic fuel injection application.
An EFI uses computers and sensors to better understand external conditions, helping to decide what the optimal airflow/fuel mix should be. This reduces poor performances but mitigates excessive fuel usage.
EFI systems can simply be an application that “injects” fuel into the airstream, when it’s needed, e.g. during cold conditions.
An EFI system will use an engine control unit (ECU) to control the series of events to provide optimal engine performance. By reading and interpreting all the available data the sensors are collecting, the ECU can ensure the engine gets the right amount of fuel and airflow to start. By leveraging technology and advanced sensors, this can make a motorcycle owner’s life a lot easier, with this all being automated in the background. However, if there are any problems, given the greater use of applications, fixing it can often require looking at the electronics.
While some may prefer the hands-on approach of carburettors and manually controlling the choke, others may welcome a more automated approach. Whatever your preference, EFI systems are increasing in usage and popularity so are likely to continue to grow within the world of motorbikes.
Learn More with Venhill
Regardless of whether you are a traditionalist and are sticking to carburettors or just purchased a new bike with EFI, our range of motorcycle cables and products here at Venhill are designed to help you get more out of your bike. We ship our products to Distributors all over the world and sponsor some of the best MX and Superbike race teams in the U.K.
Our part finder is a great place to start, making it easy for you find the relevant cables and hoses for your motorcycle for your own unique circumstances and preferences.
Our team are always on hand to help guide you in the right direction and ensure you feel comfortable in whatever you need.
See more: Types of Motorcycle Engines