If you ride a motorcycle, you will know what engine braking feels like. Close the throttle at any speed, and the bike immediately slows down. While this can be an effective way to add to the stopping power of your brakes, how bad is it for your motorcycle?
Engine braking by closing the throttle of your motorcycle while riding will not cause any damage to your motorcycle and can be an effective way to reduce the speed. Selecting a lower gear at high engine speeds without rev matching, or locking up the rear wheel, may wear out your motorcycle’s clutch faster.
Regardless of what bike you ride, you will be using engine braking to some extent, whether you are aware of it or not. The only time you are not using engine braking on your motorcycle is when you’ve got the clutch lever pulled in.
Engine braking may be entirely harmless to your bike, but get it wrong and it could cause premature wear on some components or it could be downright dangerous.
Will Engine Braking Harm My Motorcycle?
Normal engine braking that you’ll experience when rolling off the throttle while moving will not harm your motorcycle. You are simply restricting the airflow into the intake manifold and, on a fuel injected bike, shutting off the fuel delivery. The engine will still run due to being moved by the gearbox as the bike rolls on. The wear on the engine is much worse under normal accelerating.
If, on the other hand, you are downshifting aggressively while engine braking, you may be accelerating the wear on some components. Selecting a lower gear while moving at a certain speed will instantly increase the engine speed when you release the clutch lever. The engine will now be travelling faster than the gearbox (which is determined by the speed of the rear wheel). Engaging the clutch will result in slipping of the clutch plates until they are fully engaged and rotating at the same speed.
One way to avoid too much clutch slipping while downshifting, is by employing a technique referred to as ‘rev matching’. This is achieved by blipping the throttle while the clutch is disengaged. You need to apply just enough throttle to raise the engine rpm as close to the anticipated engine speed in the next lower gear you are selecting. This will ensure that the engine and gearbox are moving at the same speed when you release the clutch lever and engage the clutch plates.
If you downshift even more aggressively while the engine is at a high rpm, you may lock up the rear wheel when dropping the clutch. This will not only wear out your clutch, chain, sprockets, and rear tire, but could result in a skid and losing control of the motorcycle. You may have noticed the rear tires of MotoGP racers slide a bit before a sharp corner. That’s as a result of aggressive engine braking.
What to Avoid When Engine Braking on a Motorcycle
Engine braking is a great way to assist your brakes with stopping power, but trying to stop the bike with engine braking alone is not a good idea. You have much more control over the stopping power by applying the brakes, which can be modulated as the speed and road conditions dictate.
If you have enough time and space to plan ahead, simply closing the throttle will slow you down most of the way, but keep a look out in your rear view mirror, as you won’t be indicating your intention to slow down or stop. Feathering the rear brake to light up the brake lamp is a good idea to let the cars behind you know that you are about to stop.
Aggressively downshifting to slow down may be fun, but don’t go into the red line and keep it smooth by rev matching. Your clutch will thank you by staying alive for longer. Try not to lock up the rear wheel, as it may result in an uncontrollable skid.
Benefits of Engine Braking on a Motorcycle
Engine braking on a motorcycle has many benefits, including: (1) saving the brake pads, (2) increase stopping power in combination with the brakes, (3) preventing a runaway bike down a steep hill, (4) getting ready to pull away in the correct gear, and (5) saving fuel on a fuel injected bike.
More stopping power
The main benefit of engine braking is that it adds to the stopping power of the front and rear brake. This will save your brake pads, but more importantly, it will help you stop faster. When slowing down from 60 to 40 mph, you can employ engine braking effectively without applying any brakes. And if you need to slow down quickly, combining engine braking with both brakes will slow you down much faster. I used to do this often on my old KLR 650, which didn’t have the best brakes.
Preventing a runaway bike down a hill
When riding down a steep hill where you need to keep using your brakes to slow down the motorcycle, it is much better to use engine braking. By selecting a lower gear before the descent, you can ride downhill without applying the brakes, just relying on the engine to keep the speed down. This will prevent the brakes from overheating and fading. Big trucks do this all the time.
On very steep off-road sections where traction is limited due to loose rocks and gravel, applying the brakes too firmly may result in either wheel locking up and a loss of control. By riding down in a lower gear, you can effectively use engine braking to keep to bike from running down too fast. You can then use the brakes lightly to slow the bike even more.
Many riders pull in the clutch while slowing down and coming to a stop in order to save fuel. The idea is to let the engine speed drop to an idle while you brake. This may work on a motorcycle with a carburetor, but on a modern bike with fuel injection, engine braking is even more efficient. When you close the throttle, the fuel supply is cut off entirely. This uses less fuel than idling with the clutch in.
Getting ready to ride off
An indirect benefit of engine braking is the fact that you will end up in a low gear due to downshifting as you slow down. This will have you ready to take off if the need arises. Yes, you can hold in the clutch and kick down through the gearbox at a standstill, but that is not the best way to stop a bike. To read more on how to smoothly stop a bike the right way, check out this post.
How Does Engine Braking Work?
Engine braking happens when you close the throttle while the motorcycle is moving in gear. The engine requires a constant flow of air to combust the fuel vapor. Shutting off the throttle will close the throttle valves, restricting airflow into the intake manifold. This creates a partial vacuum in the intake manifold which works against the pistons trying to suck in air, resulting in the bike to slow down.
I’ve also read that, depending on the bike, around 20-30% of the engine power is necessary to overcome the internal friction of all the moving parts. When you shut off the power, this internal friction is what slows the bike down. Engine braking is more pronounced at higher rpm, and therefore, downshifting while moving will increase the engine braking effect.
Final Thoughts on Engine Braking
Using engine braking to assist the brakes to slow down your bike is common (and good) practice. As with most things in life, if you are not a hooligan, there’s nothing wrong with it and it won’t harm your motorcycle. If you are stopping your bike the right way, you are already using engine braking.
Practice matching the engine and road speed by blipping the throttle, and you’ll be engine braking like a pro in no time.