Honda CBR300R Engine


The Honda CBR300R is a fun, affordable sport bike that’s great for beginners, but it doesn’t quite have the same power as some of its competition from other brands. That said, it’s still got plenty of torque and is more than capable of getting you where you need to go without breaking down or needing maintenance constantly.

Engine Type Single-cylinder four-stroke

The CBR300R’s engine is a 286cc single-cylinder four-stroke. That means it has one cylinder and four strokes, with the piston moving up and down (and up and down). The engine’s bore and stroke are 76.0mm x 63.0mm, which determines its displacement (286cc) and its dimensions.

The bore is the diameter of the hole in a cylinder through which air/fuel mixture enters during combustion. The stroke is how far up or down that hole goes when it changes direction to prepare for another cycle of combustion. In this case, both measurements were chosen based on how much power Honda wants to produce from this engine as well as how long they want it to last before needing maintenance work done on it again

Displacement 286cc

The CBR300R’s 286cc engine is a large displacement for a 300cc bike and a small displacement for a 600cc bike. The same can be said of the Honda CBR250R’s 249cc engine and the Honda CB500F’s 471cc one.

The name “displacement” refers to the volume of air or fuel that can pass through an engine in one minute as it goes from zero rpm to its maximum power output. In this case, 286 cubic centimeters (which equals roughly 3 liters) per revolution or rev per minute gives us exactly what we need to know: This is an engine with ample strength under its hood, but not so much that it’ll overwhelm you on your first ride out because you’re still getting used to things like shifting gears and braking properly—and maybe even turning left!

Bore And Stroke 76.0mm x 63.0mm

The bore and stroke of the CBR300R’s engine is 76.0mm x 63.0mm, which means that it has a bore/stroke (B/S) ratio of 1.15. The B/S ratio determines the size of an engine and its power output, as well as many other factors such as fuel economy and emissions control efficiency.

Induction PGM-FI, 38mm throttle body

The way the PGM-FI system works is that a number of sensors gathered information about the engine and its environment. The data from these sensors is fed into a computer which compares them with previous inputted data and then determines how much fuel needs to be injected into each cylinder. This process is repeated continuously throughout operation so that the system can constantly adjust itself depending on conditions such as temperature, load, or engine speed.

The 38mm throttle body allows for more air flow than would normally occur through your typical carburetor because there’s no restriction caused by vaporization at high rpm (a symptom of carbs).

Ignition Computer-controlled digital transistorized with electronic advance

The ignition system is computer-controlled and uses digital transistorized ignition with electronic advance. The system is controlled by the engine control unit (ECU), the ECU configures the timing based on a number of variables, such as engine temperature and fuel mixture.

The bike is fitted with an NGK spark plug which has a heat range of J8A-10/14 and an operating voltage of 14 to 16V at 1,200 rpm when fully warmed up

Compression Ratio 10.7:1

The compression ratio is a measure of the engine’s efficiency. It refers to the ratio of the volume of cylinder when piston is at bottom dead center to the volume of cylinder when piston is at top dead center. A higher compression ratio allows for more power output from an engine, but also requires a higher octane fuel like leaded gas or racing fuel to prevent detonation (an uncontrolled combustion).

Valve Train DOHC; four valves per cylinder

The CBR300R uses the same Honda SOHC single cam, but has a different cylinder head. Because of this, it is not possible to swap a CBR300R engine into a CBR600F4i.

The valve train consists of two valves per cylinder: one intake and one exhaust valve. These are operated by dual overhead cams (DOHC) which are located in opposite sides of each other on top of the cylinder head. Each camshaft operates two valves, so there are four total valves per cylinder: two intake valves and two exhaust valves.

Transmission Six-speed

The CBR300R’s gear ratios are very similar to the CBR250R, with a first gear that is nearly twice as long and a sixth gear that’s over 40% shorter. This makes the 300 feel more like a real sportbike on the street.

The clutch has been updated since 2012, so it doesn’t require such a heavy pull anymore and provides smoother operation with less slippage. It also has an assist spring to make starting easier when pulling out at intersections or quickly moving off from stops.


You now have a good understanding of what makes up the Honda CBR300R’s engine. We hope you’ll put your new knowledge to good use, or perhaps impress your friends with some high-minded talk about displacement and bore and stroke. Either way, we’ll see you at the next car show!


So there you have it, a quick rundown of the Honda CBR300R’s engine. I hope this article has helped you to understand how this bike works and some of its key components. If there are any questions then please feel free to leave them in the comments below or contact us directly!

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