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Why Do Some Motorcycles Have Two Throttle Cables?

Why Do Some Motorcycles Have Two Throttle Cables?

Earlier motorcycles used to come with a single throttle cable.

However, as time passed, more manufacturers began to add two throttle cables to improve motorcycle security. Pull and push cables have different functions. The pull throttle cable opens the throttle, while the push cable closes the throttle.

This article discusses why some motorbikes have two throttle cables.

1. Motorcycle Throttle

A motorcycle’s overall configuration depends on how well the throttle response is calibrated. It maintains and controls the air-to-fuel ratio in the engine. However, its role can differ between motorcycle types.

Specific motorbike types are created with different throttle designs.

The throttle cable pulls or pushes the slide of the throttle within the carburetor, controlling the flow of the fuel-air mixture within the engine and operating the carburetor valves.

2. Double Throttle Cable System

Motorcycles have become more powerful over years, with many now fitted with Constant Velocity (CV) carburetors. For these carburetors, a cable controls the air volume by operating the slide throttle valve. It also controls the up-and-down movement of the slide.

For a CV carburetor, the single-pull throttle cable is inadequate to operate the spring-loaded slide. Hence, a dual-throttle cable system was introduced, particularly for twin-cylinder motorcycles. One cable (pull cable) is responsible for opening the throttle while the other cable (push cable) closes it.

3. Why Do Some Motorcycles Have Two Throttle Cables?

The two throttle cables, the pull and push cables, have different uses.

The pull cable is used to open the throttle, while the push cable closes it. The push cable acts as a safety feature in case the spring on the throttle body fails, ensuring that the cable returns the throttle to the closed position.

4. Difference Between Push and Pull Throttle Cables

A motorcycle engine needs fuel and air to run. The throttle opens the valve on the carburetor and allows air to enter the intake manifold due to the pull cable.

The pull cable pulls the throttle plates, opens the valve, and lets air in when you turn the throttle. While the push cable doesn’t actually push, it is a useful safety feature. There is a spring that closes the valve when the throttle is not activated; if this spring fails, the push cable automatically closes the valve.

Besides having different functions, the cables also differ in length and only the pull cable can be adjusted.

These cables also have different fittings and must be bought separately since they cannot be used interchangeably.

Shortly, both pull and push throttle cables have different functions, lengths, and fittings.

5. Should You Remove the Push Throttle Cable from Your Motorcycle?

Removing a push cable from your motorcycle is illegal in some countries. Research motorcycle laws for your state, region, or country before you consider removing the push cable from your motorcycle.

A motorcycle can operate fine with only one cable, but it doesn’t mean there are no risks involved. Some riders have stated that their motorcycles ran more smoothly when they removed the push cable. If this is the case, it is possible that the cable was installed incorrectly.

The push throttle cable helps improve safety since it offers another option in case the throttle spring fails. So there’s no reason to remove the push cable as it has a purpose.

6. Installation of Pull/Push Throttle Cables

Take note of the position of the original pull and push cables before installing the replacement cables. Also, make sure both cables have identical dimensions so they don't stretch over time.

Before installing the cables, lubricate them with some light oil. Hold the cable upright, apply the oil, and rub the length of the inner to ensure it is properly lubricated.

When installing the cables, keep them away from any parts that produce high heat and ensure the cables can move freely. Always install and adjust the pull cable first.

For lubrication, use a small amount of copper grease instead of heavy grease since the latter can restrict the movement of the cable, trap dirt, and cause excessive wear on the cable.

Once you finish installing the cable, lock the steering and check the operation of the throttle cables.

7. Last Words

Many motorcycles come with two throttle cables, each with a different function. The pull cable is most crucial for the motorbike as its purpose is to pull the valve and open the throttle. On the other hand, the push cable is not a necessary feature, but can act as an extra safety measure by closing the valve and throttle in case the throttle spring fails.

If you want to improve the overall look of your motorcycle, you can install saddlebags, touring packs, sissy bar bags, tank bags, crash bars, sissy bars, fairings, luggage racks, and handlebars.

Reading next

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How Does a Motorcycle Fuel Gauge Work?

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