Forced induction : why it is rarely used in motorcycles.

This question arises when I see a Kawasaki H2. It is a technological marvel in the automotive field; how could it not be? A 1-liter DOHC Kawasaki engine can produce a 300-hp motorbike; no other manufacturer can match it for now.

Those powers are available in the Kawasaki H2R, which is their race-version motorcycle and for the road version, Kawasaki provides a 231 PS engine, but that is still a lot of power when compared to other motorcycles. For the same size, only the Aprilia RSV4 with 217 HP came close, yet this is a feat of engineering that cannot be underestimated.

I suppose the difference is in the boost settings and some parts in the engine; clearly, 300 HP is not really needed for a daily motorcycle.

Kawasaki’s not new to this turbocharging game. Back in ’78, they released the Z1R-TC, which was basically a Z1R with a turbocharger. It all started when a Kawasaki executive, Alan Masek, decided to buy a bunch of Z1Rs and give them a turbocharged makeover. The idea was to get Kawasaki back on top.

So Masek teamed up with a guy named John Gleason, and together they turned the Z1R into a turbocharged beast. Kawasaki wasn’t officially involved, but they were definitely keeping an eye on things. Gleason ditched the old carbs and exhaust system and replaced them with a turbocharger, a new exhaust, and a different carburetor.

The result was a motorcycle that was capable of producing 130 HP from a 1.0-liter 4-cylinder engine, something unheard of at the time. It was faster than the Suzuki GS1000 and about 40 HP higher than the stock Kawasaki Z1R. Maybe you could say it was not an official motorcycle from Kawasaki but let’s agree that they made a breakthrough with this one.

Honda didn’t want to be left out, either. They made the CX500TC in 1982, but it only lasted a year. They replaced it with the CX650T, which also didn’t stick around for long. After that, supercharged motorcycles kind of disappeared until Kawasaki dropped the Ninja H2 in 2014.

The base for this turbocharged bike was the Honda CX500, which wasn’t super popular but had a cool feature: liquid cooling. That was a must because the turbocharger would make a ton of heat and could mess up the engine if it was air-cooled.

The CX500’s V-twin engine is a bit weird. It’s tilted at a weird angle and the head is rotated to make sure the rider’s knees don’t get in the way. The gearbox is right under the crankshaft and spins the other way to help keep the bike from leaning too much when you accelerate hard.

They added a fairing and a turbocharger to the CX500TC, but no intercooler. That means it gets really hot, which is why the liquid cooling is so important.

This thing was pretty powerful for its time. It could hit 82 horsepower and go over 120 mph. But the most important thing was the big “Turbo” logo on the side. Turbochargers were a must-have in the 1980s if you wanted to be fast and cool.

They only made about 7,000 of these bikes, so they were pretty rare back then and even more now. Prices for surviving examples have been going up, along with other turbocharged bikes from Yamaha, Suzuki, and Kawasaki.

Back in 1996, when Honda dropped the CBR1100XX, speed traps were going wild again. It was a super-fast sport tourer, built to take on the Kawasaki ZX11. The CBR could hit 177 mph, which was pretty impressive at the time. But just a couple years later, Suzuki blew everyone away with the Hayabusa. That thing could do 188 to 194 mph! It was like a whole new level of speed.

The Hayabusa had a bigger engine and better aerodynamics, so it was way faster than anything else out there. It was a huge jump compared to the small improvements we’d seen before. Remember, this was in the late 90s, so safety stuff wasn’t as good as it is now. Neither the Hayabusa nor the CBR had stuff like ABS, traction control, or any of those other modern safety features. It was a pretty wild time to be a motorcycle rider.

It’s no wonder Europe decided to step in and do something about these crazy speeds. They realized that these bikes were just too fast for the roads and that people were getting hurt. So, they started to introduce regulations to limit the top speeds of new motorcycles.

The Hayabusa was like a rocket ship on two wheels. It blew everyone away when it beat Honda’s top-speed record by a huge margin. And then Kawasaki hinted that their new Ninja ZX-12R was going to go even faster—maybe even hit 200 mph. People were freaking out. Some folks in Europe were worried that this would lead to more illegal street racing, so they started talking about making rules to slow these bikes down.

To avoid getting into trouble, the motorcycle companies decided to make an unofficial agreement. They agreed not to make bikes that could go faster than a certain speed. It’s a bit unclear exactly what that speed is, but it’s somewhere around 186 mph or 300 km/h. Honda said they wouldn’t make bikes faster than 300 km/h, but Suzuki and Kawasaki wouldn’t say anything about it.

So, starting in 2000, if you wanted to find out which bike was the fastest, you had to mess around with its computer. That way, the companies could say they didn’t make the bikes fast enough. It was kind of like a gentleman’s agreement to keep things fair and avoid any more speed wars.

But it seems that the regulation was slowly abandoned by several manufacturers, especially when in 2007 MV Agusta released the F4R 312, which was capable of reaching 312 km/h (194 mph) and they did not feel the need to follow or comply with the regulation “because MV sees no reason to abide by the manufacturers’ agreement … Politics be damned: MV is Italian and the Italians have a national imperative to make their bikes as fast as possible,” in the opinion of motoring journalist Roland Brown, and maybe that’s true; the speed war still exists even though it is done underground.

Until then, most superbikes were limited to 299 kmh; if you wanted to remove those limiters, you had to replace or remap the ECU and there were already several companies or workshops that could even use them on some versions of motorcycles. Some manufacturers did not use limiters in some markets, but most manufacturers were still loyal to the old regulation: 299 kmh was the maximum limit because they didn’t want to kill people.

But of all the motorcycles I mentioned, there is one thing in common: none of them use forced induction.

Kawasaki can easily get away with it because slowly those gentlemanly agreements are abandoned or manufacturers start looking for ways to bypass them. There are so many motorcycles that can reach 200 hp and can run more than 300 kmh, even though the manufacturer can limit it at 299 kmh, but all of that can be easily modified to bypass those speed limits so that the existing agreement seems useless.

It’s just that motorcycles are already fast enough and humans are at their maximum point. It is rare for someone to be able to ride more than 300 kmh on public roads, and existing technology is enough to allow for that without having a forced induction system. Kawasaki itself has proven that they can bump power up to 100 HP only with a supercharger system. If all manufacturers follow suit, I think motorcycles will be even more terrifying and faster. The joy of motorcycling will be lost and replaced by the quest for speed that has happened several times in this world.

For this matter, I think manufacturers feel the same way: adding forced induction to a motorcycle is unnecessary; motorcycles are already fast enough without it and most likely the technology will be more troublesome for its users. But the main point is speed and power; many companies may feel that forced induction is not needed.

Kawasaki (as usual) wants to be the first in its field by releasing the H2 and H2R after they saw that those agreements were no longer being observed. Previously, manufacturers did not want to experiment crazier because they were still subject to those agreements and did not want to leave them. It could be that after this, there will be several manufacturers who follow suit and release supercharged/turbocharged motorcycles; only time will tell.

And maybe the technology is only possible now. In the case of the Honda CX500TC, the main complaint was turbo lag, which ultimately made riders dislike it and it is possible that at that time the technology did not allow it. Now everything is possible because the technology is sophisticated and there are many systems that support it.

So, it seems forced induction has not been used much in the motorcycle world for decades because manufacturers have not found a way to make it efficient, especially in terms of size. It requires compact and neat plumbing, while most sportbikes have narrow engine bays. Installing a forced induction system has not been easy for decades and maybe only Kawasaki can find a way for now.

Most manufacturers are also worried that their steps to increase horsepower will make the relevant parties angry and finally give them a ban again, like in 1999 so they don’t make motorcycles with forced induction so that those regulations don’t come again. At least being banned is not pleasant and it will hinder the development of their motorcycle technology.

Even so, motorcycles are fast enough and it seems we are already at the maximum speed when riding a motorcycle, but let’s see what the Kawasaki H2R will bring to us. Will those horsepower wars return or will everyone submit to the regulations? Only time will tell.