To slowdown a motorcycle, you can either use the front or rear brakes. Or, you can slow down by rolling the throttle down to decelerate your bike – which is known as engine braking.
So, is engine braking bad for motorcycle? Engine braking is decelerating your motorcycle by rolling the throttle down instead of using brakes. Engine braking is not at all bad for your motorcycle. It in fact improves life expectancy of brake pads and enhances fuel efficiency.
One thing to keep in mind is that you should also downshift the gear to match the road speed while engine braking. Most motorcycle riders do this knowingly or unknowingly. And this is a riding practice that is useful in the long term.
The Science Behind Engine Braking
In a motorcycle, during the intake stroke, the piston moves down to fill the cylinder with air and fuel. When you accelerate, the butterfly valve opens and air enters the cylinder. This mixture is then combusted during the combustion stroke to produce energy that moves the wheels.
During engine braking, you release the throttle and intake of the air stops. But the piston continues to move down during the intake stroke. This creates a vacuum in the cylinder which resists the further movement of the piston and thus drags the wheel. This in turn slows your vehicle.
When the engine brake slows the RPM of the engine quicker than that of the rear wheel, the rear wheel begins to move the engine. But since the engine is working against this force, it finally slows down the vehicle.
Sometimes during engine braking, the rear wheel tries to move the engine faster than it has to under engine braking. This makes the motorcycle lose traction and shaky. To prevent this, nowadays motorcycles come with Slipper Clutch also known as back-torque limiter. This partially disengages or slips when the rear wheel tries to move the engine faster than the expected speed until the speed of the rear wheel matches with the speed of the engine.
Is Engine Braking Good Or Bad For Your Motorcycle?
People have different opinions on this. The argument on whether the engine braking is good or bad is still going on.
But, if done correctly, Engine Braking is really good for motorcycle. It can even protect your vehicle in many ways.
Some of its pros are as follows,
It reduces the wear and tear of the brake. If you hone this skill, it reduces the use of brakes thus protecting the brakes.
It also helps in preventing accidents during emergency situations.
In addition, since you will be using brakes much less frequently, engine braking enhances the life expectancy of brake pads.
Also, the gas mileage of your motorcycle will improve since the fuel is not wasted as you use throttle more and more to adjust your bike speed.
However, there are some minor downsides to engine braking in the following conditions.
- In few motorcycle models, especially old ones, the rear lights brighten only when you apply brakes. If done in traffic, it might lead to accidents, since the vehicle behind you won’t get a signal that you are slowing down. In such cases, you can use brakes along with engine braking just to signal the follower.
- If you are a beginner, then you must be careful while engine braking and downshifting, because it might lock up the rear wheel and you might skid.
- Since the rear wheel is moving faster than the engine, some might feel it is difficult to control the vehicle. But what you have to do in such a condition is just to downshift your motorcycle and it comes under your control again. Or if your bike has a slipper clutch, it solves the problem.
Let’s Bust Some Myths
There are some myths around engine braking which should not be taken seriously here.
Lack of Lubrication in the Engine
It is said that Engine Braking can lead to a lack of lubrication in the piston.
As I have explained earlier, if you are using engine braking in a two-stroke engine, then the engine can suffer a lack of lubrication. But in a four-stroke engine, there will be a separate oil pump to lubricate the engine which has no connection with you closing the throttle.
Premature wear of transmission and clutch
Of course, I can’t completely disagree with this one, because if one doesn’t downshift the gear to match the road speed then it can lead to wear of transmission and clutch.
But if you are doing it perfectly, i.e., downshifting and rev-matching while engine braking, then it won’t harm the transmission and the clutch.
Engine Braking In 2-Stroke And 4-Stroke Motorcycle
Engine braking does not work in the same way in a Two-Stroke and a Four-Stroke engine. It works best in a four-stroke engine but at the same time, it might harm a two-stroke engine.
To understand this we should know the difference between a Two-Stroke and a Four-Stroke Engine.
A two-stroke engine completes one cycle of Intake, Compression, Combustion and Exhaust in two strokes i.e., up and down movement of the piston. In such engines, the intake and exhaust take place simultaneously, and there are no intake and exhaust valves.
For two-stroke engines, the lubricant should be mixed with the fuel. So, when you engine brake, no lubricant or only a little lubricant enters the engine. This leads to a scarcity of lubricant in the engine. This might seize the piston.
If you use the engine brake only a few times, it might not harm the engine much, but if it’s done often it even leads to a seized piston which definitely costs you more than a brake pad.
So, it is better not to use the engine brake in a two-stroke engine.
A four-stroke engine completes one cycle of Intake, Compression, Combustion and Exhaust in four strokes. Here the piston moves up and down twice to complete the cycle. Hence they have Intake and Exhaust valves.
When the piston moves down the Intake valve opens and the Exhaust valve closes. The air and the fuel enter the cylinder, this is the Intake Stroke. Once the cylinder fills, the intake valve shuts and the Compression Stroke begins where the piston moves up, compressing the mixture of air and fuel.
In the Combustion Stroke, the compressed mixture of fuel and air is ignited which releases energy. This energy forcefully pushes the piston down. And in the Exhaust stroke, the piston moves up again and at the same time, the Exhaust valve opens to push the energy out.
The internal pressure is more in a four-stroke engine, hence engine braking works better on such engines. Also, four-stroke engines have a separate oil pump for lubrication purposes, so the engine will be lubricated well even if the throttle is closed.
When To Use Engine Braking?
Use Engine braking while riding downhill.
Engine braking is very helpful while riding downhill. You just need to lower the gear and use the engine brake. This reduces the use of the brake thereby preventing overheating of the brake. So, brakes last longer.
This skill can definitely save you from emergency situations.
You are riding and the person in front of you suddenly stops. What will you do?
In such emergency situations, engine braking skill comes handy. Because by using engine braking and downshifting in such a situation one can maintain an appropriate gear with the required speed, which helps to accelerate immediately without changing the gear at the moment. Also, using engine braking along with the brake you can stop your motorcycle even if the distance is very short.
It is a very useful skill for racers
It is a very useful skill for riders, especially for cornering. It helps them slow down for a corner and also be in the rev range of the engine.
Be careful in traffic though
When you slow down using the brake, the red light that glows gives a warning to your follower that you are stopping or slowing down.
However, in few motorcycle models, especially old ones, the rear lights brighten only when you apply brakes. If done in traffic, it might lead to accidents, since the vehicle behind you won’t get a signal that you are slowing down. In such cases, you can use brakes along with engine braking just to signal the follower.
Engine braking is a skill that comes gradually by practising. Over time it will become a habit that is very handy.
If you master the skill of using both front and rear brakes in conjunction with the engine braking technique it will increase the proficiency of your motorcycle.
As such, Engine Braking is not at all bad for your motorcycle. In fact, it is good for your bike since it comes with so much pros as we discussed above.
So, go ahead with engine braking whenever you feel so during your next ride.