There is a certain Yamaha sport motorcycle with full fairings meant to be ridden hard and fast, with the rider being subject to that somewhat cramped, aggressive rider triangle. At first glance, it resembles a liter bike, or at the very least, one of those 4-cylinder screamers that are so common in these types of motorcycles. But the bike in question doesn't have a 4-cylinder engine. Instead, it has the very versatile and competent parallel-twin CP2 Engine. The motorcycle in question is the Yamaha R7.
Capable of blasting past most anything on the highway, and yet, there's the absence of that characteristic four-cylinder sound. It matters not as the 270 degree crankshaft CP2 Engine from Yamaha sounds quite distinctive and aggressive as well, while at the same time delivering outstanding performance. When Yamaha put the CP2 engine on the Yamaha R7, some almost felt as if something was off with that picture. But in reality, there’s nothing really wrong with it is there? The performance that thing delivers is astonishing, after all. Worthy of any good sport bike. And reducing the number of cylinders is actually a trend in the motorcycle industry. Being a tried and tested, efficient, full of low and mid-range torque, and powerful engine, it comes as not surprise that Yamaha uses it in several models. The Yamaha R7, the MT-07, the modern classic XSR700, and the Yamaha Ténéré 700 all have that one thing in common. They’re all powered by the extremely versatile CP2 Engine.
4-Cylinders Are Becoming Less Common
The 4-cylinder crew loves that high-pitched scream those engines make when revving them up. There is a lot of history when it comes to 4-cylinder engines too. But there is also no shortage of riders who thoroughly enjoy a high-performance V-twin or parallel-twin. One cannot deny America’s love of the classic V-twin sound. There’s nothing quite like it. The classic Harley V-twin, for example, has the two cylinders arranged at a 45-degree angle from each other. This configuration, along with the single crank pin, among other features, creates uneven power stages during the strokes of the engine and helps create that iconic sound.
The Parallel-twin, on the other hand, might not have the same architecture as its V-twin counterpart, but it can be engineered to be more efficient, and still feel and sound similar. A Parallel-twin, only needs one cylinder head, one camshaft drive, and two cams, resulting in it needing fewer parts than a V-twin, making it lighter and less expensive to manufacture. The sound is all over the place though, depending on the crankshaft used. The CP2 has a 270-degree crankshaft, which is, by the way, the same setup seen on the versatile Honda Africa Twin. If a full rotation is 360 degrees, 270 is three-quarters of that, this means one piston follows the other from a “distance” of 3 quarters of a rotation. So, the second cylinder fires 270 degrees after the first, and then there is a gap of (360 x 2) – 270 = 450 degrees until the first cylinder gets to fire again, resulting in uneven firing intervals, giving the engine some character, and the feel of a good V-twin.
The CP2 Engine Is Good At Basically Everything
Yamaha’s CP2 engine, being liquid-cooled allows for it to run at controlled temperatures even when pushed hard, and still boast a high compression ratio of 11.5:1. Using an in-house example for comparison, the air-cooled Yamaha Bolt R-Spec has a compression ratio of 9.0:1. Compression ratio can be explained as being the ratio between the volume inside the cylinder at its largest capacity and its smallest. A higher compression ratio such as the one seen on Yamaha’s CP2 engine has several benefits. For starters, the combustion process is optimized with a more complete burn of the air and fuel mixture inside the combustion chamber. As a consequence, power output is improved, as well as fuel economy because of this efficiency gain. If more power is being extracted from a certain amount of fuel, then less fuel is needed to produce the same amount of work, which also translates to better emissions. Finally, a high compression ratio allows for better torque at low engine speeds. The first Yamaha to use the CP2 engine was the FZ-07 back when it was first introduced in 2015, and the name was later changed to MT-07, to match the model name throughout the rest of the world. MT stands for Master of Torque, which is quite a fitting description for the CP2. With this engine powering it, the MT-07 went on to become one of Yamaha's best-selling models.
The CP2 Had Big Shoes To Fill
The bike the FZ-07 replaced was the 600 cc, 4-cylinder Yamaha FZ6. The 600 cc engine used on the FZ6 made just over 90 horsepower at the crank. This one was a screamer, and its redline came at 14,000 RPM. This was a slightly detuned version of the engine used on the Yamaha R6, which produced a few more ponies and has a redlined of 15,500 RPM.
To give credit where credit is due, the acceleration of those 100+ horsepower 600 cc sport bikes from the early 00s like the Yamaha R6 through the gears thrilled riders from all walks of life. But they needed to work the bike hard to get to where the real power was, and then work some more to keep it there. The CP2 engine produces more torque at lower RPM and has more useable power on tap at any given moment. It’s a better engine in terms of overall performance, at least most of the time. It can be ridden gently and relaxed in an everyday commute, and even then, the second the rider twists the throttle wide open, it's time to hold on for dear life. It does everything really well, even though it has to be said there is a bias towards low and mid-range torque, but that’s fine as it is what most riders need anyway.