Honda’s recent patent application for a radical but potentially viable future four-cylinder superbike showed that the firm has an eye on using its technological might to return to the top of the sportbike heap. Now it’s been backed up by a host of other patent applications that may well be part of the same project.
In a spate of patent filings, Honda has published several documents about individual projects that all seem to revolve around the idea of getting more performance from an inline four-cylinder superbike. The implication is that these aren’t projects related to the firm’s V-4 MotoGP bike, but instead are exploring how to make a big step forward with the Fireblade or its successor—potentially the machine we revealed here.
The first batch of new patent applications relate to a project we actually scooped nearly three years ago: an inline four-cylinder engine with variable valve timing and lift. It’s a design that hasn’t changed much since the initial patent applications back in 2019, but the additional documents were filed with the Japanese patent office more recently, in 2020, and not published until October 2021. The additional patents show detailed tweaks to the design, including the addition of electronic sensors to monitor the position of the variable valve system and alterations to some of the mechanical elements, but the overall idea remains the same.
Overall, it’s not unlike the BMW ShiftCam system that’s used on the latest R 1250 models and the S 1000 RR. There are two possible cam lobes for each valve (unlike the BMW setup, Honda’s VVT design alters the exhaust valve timing and lift as well as the intakes), and the lobes themselves are shifted sideways on splined camshafts to switch between them. Like the BMW design, the sideways movement is achieved by inserting a static pin into a track carved into the sliding “sleeve” section of the camshaft that holds the lobes. The track means that the pin can be inserted at any time in the camshaft’s rotation, but it will only slide the sleeve section at exactly the right moment, when the valves are closed and there’s minimal pressure being exerted on the lobes.
BMW’s setup is simplified on the boxer engines by the fact there’s just one cylinder for each sliding cam sleeve, while on the S 1000 RR the sliding sections each carry the cam lobes for two cylinders. Honda’s design gives an individual set of movable lobes for each cylinder.
Another notable difference between the BMW and Honda systems is the fact that where BMW relies on solenoids to directly insert the pins into their tracks on the camshafts, Honda’s design uses oil pressure diverted by an electronically controlled valve. In turn, that pressure moves a rod which is shaped to either one or other of two sprung pins to engage with the tracks in the camshaft’s sliding sleeve sections. Depending on which pin is engaged, the sleeve moves to bring either an aggressive lobe into play, with more valve lift, duration, and overlap for high-rpm performance, or a milder lobe for better economy and emissions at lower engine speeds.
Given the ever-increasing pressure from legislators to reduce engine emissions, and the equally powerful demands from customers for increased performance, variable valve timing and lift systems are likely to be one of the key weapons for manufacturers hoping to extend the life span of the internal combustion engine in motorcycles. Honda was a pioneer of such setups on four wheels, so when the company finally decides to adopt true variable valve timing and lift on a motorcycle (as opposed to the Hyper-VTEC and REV systems used since the 1980s, which simply deactivate half the valves), it’s likely to set a new standard for their effectiveness.
The second new set of patents that has emerged in relation to four-cylinder superbikes from Honda all focus on methods to make the main coolant radiator smaller and lighter than current designs. Patents have been applied for on at least three separate new ideas, all shown mounted on drawings of a generic, CBR-style sportbike.
The first reveals a cooler made up of wide-spaced water channels interspersed with thin fins like a conventional radiator but formed into a horseshoe shape to neatly sit around the front wheel, allowing the distance between the wheel and engine to be reduced. To ensure it still cools well, the design’s depth varies, with a much thicker section of the top tapering into thinner sections at the ends of the horseshoe shape.
The varying thickness idea is carried over into the second of the new radiator patents, which reveals a V-shaped cooler, incorporating a header tank into the top and with a profile that’s much thicker at the top than the bottom to help it fit into the confines of a superbike’s fairing.
Finally, there’s an unusual circular radiator design, more like the coolers used on computer CPUs than a conventional rad. Once again, it’s thick at the top and thin at the bottom to fit into the available space, but this idea relies heavily on a fan rather than just the airflow running past the bike. There’s a central hole where the fan motor sits, and the whole fan is inset into the radiator, forming its own shroud to make it as effective as possible.
While not all these patents will turn into production realities, it’s clear there’s currently a push into developing unusual ideas to improve faired sportbikes with internal combustion engines at Honda. After many years of following the herd instead of leading it, a return to the Honda that brought us mold-breaking machines like the NR750 and RC30 can only be welcome.