What is the Throttle on a Motorcycle? [Video]


Simply put, the throttle on a motorcycle is actually the right handlebar grip. This type of throttle is known as a “twist-grip throttle” as you have to twist the grip with your wrist to control the engine. The throttle on a motorcycle is used for controlling engine power by varying the quantity of gas and air entering the cylinders.

If you want to find out more about how the throttle works on a motorcycle, this post is for you.

We at PowerSportsGuide have compiled the basics of this key part under one roof!

Contents show

What is the Throttle on a Motorcycle?

The majority of powersport vehicles are powered by internal combustion engines, and motorcycles are no exception.

Although the layout of motorcycle engines varies widely, basically all of them work in the same way. They burn a fuel and air mixture in their cylinders to produce energy.

The power of these engines can be increased or decreased by regulating the amount of this air/fuel mixture streaming in. To control this stream, you need a mechanism that is easy to handle while riding.

This is where the twist throttle comes into play!

The throttle on a motorcycle is designed to regulate the amount of the air/fuel mixture, so the level of engine power. The more throttle you apply the more engine power is delivered, which ultimately results in faster acceleration and higher top speed.

Are you curious about how the throttle works?

Keep reading!

What does the Throttle do on a Motorcycle?

What does the throttle do on a motorcycle? Contrary to popular belief, the throttle on a motorcycle doesn’t directly regulate the amount of gas entering the engine. Instead, what the motorcycle throttle does exactly is control how much air flows into the engine. Before the air reaches the cylinders the right amount of gas is mixed into the air automatically.

Let’s see exactly how this happens!

How does the Throttle Work on a Motorcycle?

The throttle on a motorcycle works in a very simple way. The twist throttle (right grip) is directly connected to the throttle valve with a cable. But on some of the newest motorcycles the throttle is controlled electronically. Twisting the throttle opens the valves, which allows more air to enter the engine. The wider you open the throttle the more air and gas flows into the engine, which finally results in more power.

There are two main types of motorcycle engines, carbureted and fuel injected engines.

The main difference between these designs is the way they mix the gas with air.

The carburetor uses a little trick for this, known as the “venturi effect.”

When air flows through the carburetor it’s forced into a narrow tube. In this tube, the speed of the air increases, which causes its pressure to drop.

This decrease in pressure generates a suction effect that pumps gas up from the bottom of the carburetor.

In contrast, in a fuel-injected motorcycle engine the gas is forced into the air by injectors.

The injectors work like spray nozzles and add gas to the air as a fine spray.

In a carbureted motorcycle engine, the throttle valve is mounted inside the carburetor. In contrast, in a fuel-injected engine the valve is placed at the entrance or inside of the throttle body. The throttle valve in motorcycles is typically a “butterfly valve,” which is actually a small metal disk that rotates around a shaft. It works in a very similar way as a water tap.

If your bike features a regular throttle cable, the throttle valves are physically moved by this cable. If you twist the throttle, the cable opens the valves.

But if the throttle is electronically controlled, twisting the throttle sends electronic signals to the computer.

Based on how much throttle is used, the system opens the valves automatically.

Here’s a great video on how the carburetor works on a motorcycle:

How Do You Hold the Throttle on a Motorcycle?

Keeping safety in mind it’s recommended that you always hold the throttle on a motorcycle with all four fingers. The only time you have to move your fingers is when using the brake lever when you want to use the front brake. Best practice is to keep your wrist in a straight position, which results in a convenient and safe body position.

This is important as holding the throttle grip too high can lead to uncontrolled wrist movement on a bump. This can easily end in an undesired blip on the throttle and finally an accidental acceleration!

Therefore, always make sure that your forearms are parallel to the ground and your elbows are slightly bent.

This position helps your arm stay relaxed and can mitigate the negative effects of riding over a bump.

How do You Control the Throttle on a Motorcycle? 

As a rule of thumb, you always have to control the throttle on a motorcycle by twisting your right wrist. One typical mistake of beginners is that they try to control the throttle by moving their whole right arm. Unfortunately, this leads to a disadvantageous riding position. Besides fatigue, it can even cause dangerous situations.

Why?

This is because controlling the throttle with your arm moves your elbow lower, which prevents you from properly operating the handlebar.

Therefore, always make sure that your arms are relaxed, and your wrist is flat, so you can control the throttle exclusively with your right wrist.

Which Way Do You Twist the Throttle on a Motorcycle?

Which way do you twist the throttle on a motorcycle? Don’t worry, as it’s pretty simple. If you twist the throttle backward the engine RPM increases, which causes the motorcycle to accelerate. In contrast, twisting the throttle forward reduces engine power which leads to deceleration.

How do You Close the Throttle on a Motorcycle?

Closing the throttle on a motorcycle means completely cutting the engine power. To close the throttle, you need to twist the right handlebar grip completely forward. In other words, you have to lift your right wrist.

Proper throttle handling is important as you have to close the throttle every time you shift gears. (You can learn more about gear shifting on a motorcycle here.)

Why Doesn’t a Motorcycle’s Throttle Rotate in the Opposite Direction?

The throttles on motorcycles rotate backward mainly for safety and comfort considerations. Let’s face it, twisting your wrist backward is a more natural movement, which causes less fatigue and makes the ride more comfortable. Besides, when you brake hard, your momentum forces the throttle to roll forward. On top of that, you can control the throttle far more precisely by twisting your wrist backward.

The main advantage of the standard direction of rotation is that you don’t need to act against physics.

When you’re accelerating, the forces are virtually “pulling you backward.” Since you want to stay on the bike you have to cling to the handlebar, which finally causes the throttle to roll backward.

The opposite happens when you’re braking. Your momentum forces you towards the handlebar, and your wrist naturally twists the throttle forwards.

What does Rolling the Throttle Mean?

Rolling the throttle means turning the throttle grip gently, which gradually feeds the engine with the gas/air mixture. This results in a slower, more moderate acceleration. At the other end of the spectrum there is an action called “hammering the throttle” or “twisting the throttle.” This means the throttle grip is quickly rotated backward. This act causes high engine revs and a fast “race-style” acceleration.

Motorcycle Throttle Maintenance

Just like any other key part of your motorcycle, the throttle also requires attention and care. Let’s see what the typical motorcycle throttle maintenance tasks are!

How Can I Make My Motorcycle Throttle More Responsive?

The throttle response on a motorcycle refers to the engine’s responsiveness to the throttle cable/signal.

To make your motorcycle throttle more responsive you have to adjust and lube the throttle cable. Improper cable slack is the leading reason why the throttle is not responsive on many bikes. Adjusting a motorcycle throttle cable means setting its free play using the adjusters. Let’s see how it’s done!

How do I Adjust the Throttle on My Motorcycle?

You can adjust a throttle on your motorcycle in eight easy steps:

  1. Read your bike’s manual
  2. Check and mark the initial cable settings
  3. Locate the cable adjusters
  4. Use the barrel adjuster on the handlebar for smaller changes
  5. For major changes you may want to use the cable adjuster at the other end of the throttle cable
  6. Make sure the cable is not too tight (Zero free play is definitely not recommended!)
  7. Check the cable for wear and tear
  8. Lube the cable if needed

If you want to learn more about the process don’t miss this great article at MC online.

If you prefer to watch videos instead, here’s a great tutorial on how to adjust a motorcycle throttle cable:

How do You Adjust Dual Throttle Cables?

To properly adjust dual throttle cables the key is to set the same amounts of free play on each throttle cable. Here’s a great video on the process:

How Much Play Should a Motorcycle Throttle Have?

As a rule of thumb, the free play of a motorcycle throttle should be about 0.08 – 0.12 inch (2-3 mm). Although these measurements are recommended by most manufacturers, before servicing your bike it’s recommended that you check its service manual and follow the instructions.

Also, keep in mind that every motorcycle throttle cable needs a little free play.

A completely tight throttle cable (“zero free play”) would be dangerous as moving the handlebar would cause an immediate change in the throttle position.

What Causes a Motorcycle Throttle to Stick?

A stuck throttle cable on a motorcycle is most commonly caused by wear and tear on the cable, dirt inside the cable housing, or a lack of lubrication. The throttle cables of off-road bikes are particularly prone to clogging due to the dirty riding environment. However, keep in mind that a stuck throttle cable could also be a symptom of a throttle assembly malfunction as well as fuel injection system/carburetor issues.

How do You Lubricate a Motorcycle Throttle Cable?

To lubricate a motorcycle throttle cable, it’s recommended that you release it from the handlebar. If you have a cable lubricator tool on hand attach it to the end of the cable and spray some lube into the housing.

If you don’t have a special cable lubricator, don’t worry.

You can still mount a short plastic pipe onto the end of the cable housing and pour a little lubricant into it. Another trick is to make a little funnel from a plastic bag and attach it to the end of the cable with a rubber band.

Here’s a great video on how to lubricate a motorcycle throttle cable:

What is the Best Lubricant for Motorcycle Cables?

Experts say that the best lubricants for motorcycle cables are those that are specifically formulated for this purpose. These products are typically aerosol lubricants that make it easier to inject the lubricant into the cable housing. If a special cable lubricant is not available, you can also use regular motor oil for this purpose. It’s very important to never use penetrating oils like WD-40!

How do You Fix a Motorcycle Throttle Cable?

Although it’s possible to fix a motorcycle throttle cable with some DIY tricks, it’s definitely not recommended. Throttle cables are cheap and easy to replace, so it is not worth gambling with them. If you can see any wear and tear or damage on the cable or its housing, best practice is to invest in a new one immediately.

How Much is a Motorcycle Throttle Cable?

The price of motorcycle throttle cables ranges from $10 up to $100. The cheapest motorcycle throttle cables are arguably the regular “single” cables which typically cost about $10-$30. If you are looking for a stainless steel or a dual throttle cable be prepared to pay about $50-$100.

How do You Change a Throttle Cable on a Motorcycle?

Changing a motorcycle throttle cable is always tricky as the end of the cable is buried inside the engine. Therefore, depending on the type of bike you have you probably have to unbolt some parts to reach the throttle housing. Before you do this, you may want to take some pictures of the routing of the old throttle cable.

They may come in handy when you install the new cable, as it’s very important that the new cable follow the original cable’s routing.

You have to disconnect the cable from the throttle housing as well as from the handlebar.

Before you install the new throttle cable make sure to lubricate it, as new cables are typically not lubricated.

Here is a great tutorial on how to change a motorcycle throttle cable, but you also can’t go wrong by checking out this post at RevZilla.

Related Questions

What is Twist Grip Throttle?

A twist grip throttle is a grip on a vehicle that can be rotated to control engine power. A twist grip throttle is commonly used on motorcycles and smaller outboard motors as well. Surprisingly, the majority of other powersport vehicles feature a thumb throttle.

What is a Thumb Throttle?

A thumb throttle, as its name implies, is a throttle lever that can be operated with your thumb instead of your wrist. The thumb throttle is actually a small lever mounted below the right-hand grip. Thumb throttles are commonly used on ATVs, snowmobiles, and older jet skis.

Can You Put a Thumb Throttle on a Motorcycle?

Although it’s physically possible to put a thumb throttle on a motorcycle, it’s definitely not recommended. Having a thumb throttle on your motorcycle would not only be dangerous but very uncomfortable as well. Holding the throttle lever for hours would result in massive pain in your right thumb!

Why do Motorcycles Have Twist Throttles?

Motorcycles have twist throttles as this design offers the easiest and most precise handling. Unlike thumb and finger throttles, a twist throttle allows you to maintain a steady speed effortlessly as you can hold the grip with your whole right hand.

In contrast, it’s much harder to maintain the same throttle position with a thumb or a finger throttle.

What is a Throttle Cable on a Motorcycle?

The throttle cable on a motorcycle connects the twist throttle to the throttle valves. Rotating the twist throttle pulls/releases the cable, which causes the valves to open and close. Some motorcycles (typically 2-stroke dirt bikes) feature one throttle cable while most 4-stroke machines come with a dual throttle cable.

What’s more, many modern motorcycles don’t feature a throttle cable at all, as their throttle is controlled electronically.

Why do Some Motorcycles Have Two Throttle Cables?

Some motorcycles feature two throttle cables for safety reasons. One of these cables opens the throttle valves while the other closes them. It’s an important safety feature as thanks to the second cable there is no risk of the valves accidentally remaining open. The “opening cable” can be stuck, or throttle return springs can be damaged too, which does not allow the valves to close.

This is where the second “closing” throttle cable comes into play. When you twist the throttle forward this cable pulls the valves closed.

What is a Throttle by Wire on a Motorcycle?

A throttle by wire on a motorcycle means that its throttle isn’t connected to the engine with a regular cable. Instead, rotating the throttle sends an electric signal to the computer, which opens and closes the throttle valves. Since the throttle is linked to the computer with a wire, this system is often referred to as “throttle by wire” or “ride by wire” as well.

Which Motorcycles Have Ride by Wires?

More and more modern motorcycles today are manufactured with a “ride by wire” throttle system. In the past, this technology was standard only on high-end bikes, but to the delight of many fans, this feature is already available on the more affordable models as well.

For instance, you can find a “ride by wire” throttle system in the following motorcycles:

  • Aprilia RSV4
  • KTM Duke 390
  • MV Agusta Brutale 800 RR
  • Ducati Diavel Carbon
  • Ducati Monster 821
  • Ducati Monster 1200
  • Kawasaki ZX10
  • Triumph Tiger Explorer
  • Triumph Trophy (SE)
  • Yamaha R1, R6
  • Honda VFR1200F

Does My Bike Have a Throttle by Wire?

If you are unsure whether your bike has a “throttle by wire” system, just take a look at the throttle. If you can see cables coming from the right grip (other than the front brake cable) it’s a clue that your bike features this system. But if you still have doubts, it’s recommended that you check your bike’s service manual.

Why Does Your Harley Have 2 Throttle Cables?

Just like many modern motorcycles, Harley-Davidsons also utilizes 2 throttle cables due to safety reasons. One of these cables closes the throttle valves while the other opens them. It’s like having extra insurance on the bike, as the throttle valves don’t remain open even if the springs or the throttle cable get damaged.

Conclusion

The throttle assembly on a motorcycle is actually the right handlebar grip. Motorcycles feature a twist throttle, meaning that you have to twist this grip to control engine power.

Moving the throttle backward causes the motorcycle to accelerate while moving it forwards closes the throttle valves, which reduces (or completely cuts) the engine power.

The majority of bikes feature a throttle cable, in which the valves and the twist throttle are connected to a regular cable.

However, more and more new bikes are manufactured with a “ride by wire” throttle system. 

On these bikes, the throttle sends electronic signals, and the computer sets the throttle valves automatically.

References

https://motorbikewriter.com/hold-throttle-correctly/

https://www.motorcycle.com/mini-features/lessons-from-a-moron-essential-throttle-control-techniques.html

https://www.cycleworld.com/how-does-motorcycle-fuel-injector-work/

https://www.motorcyclistonline.com/how-to-check-and-adjust-your-motorcycle-throttle/

https://www.motorcyclistonline.com/motorcycle-tech-tips-bike-maintenance-how-to-lube-lubricate-motorcycle-cables-mc-garage-video/

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