Motorcycle engines are the leading engine technology field in a production vehicle. Obviously F1 would be the ultimate leading edge, but you can’t buy that technology off a showroom floor with a warranty either. Today’s 600 cc motorcycles are producing over 100 horsepower. They can also cover a quarter mile in less than 10 seconds, stock! This was something reserved for only 900 cc + bikes from just a few years ago! So then you have to ask how these engines are making so much power?
To answer this first we need to understand that an engine’s torque is directly affected by airflow. Obviously the first task of a performance engine is to increase the airflow. Every year the Japanese motorcycle companies Kawasaki, Yamaha, Suzuki, and Honda push the performance envelope. They are using light weight titanium valves, special cylinder bore sleeves, and light weight connecting rods and pistons. This is the second key to making horsepower, as horsepower is a calculation made from torque and rpm. By using all of these lightweight engine parts the rpm’s can drastically go up. The stock redline or maximum rpm that the engine should reach is 15,500 rpms!!! on many of these new 600 cc bikes. The high rpms with the ability to keep the airflow high enough is how these engines make so much power. The gearing can be very aggressive for acceleration, yet the high rpms allow top speeds in excess of 150 mph! Obviously the weight of these bikes has also dramatically dropped leading to much better acceleration times also. To give you an idea of just how high tech these engines are, your average 2 liter car engine would make 356 horsepower if the same performance! Although a drawback to this high rpm power is a lack of low end torque. Two cars using a similar level of technology often hear complaints of low torque. The Honda S2000 and the Mazda RX-8. Both have small displacement engines that make a descent amount of power. Luckily bikes are so light and always manual geared, that this lack of torque doesn’t hurt them.