Remember the XE7 turbocharged engine that Suzuki exhibited as a reference at the 2015 Tokyo Motor Show?
It was supposed to be used in the concept model Recursion (2013), but has not been released since then.
This is the non-turbo (i.e. NA) model for which a patent application has been filed for 2019, and it is expected to appear at the Milan show in November.
The XE7 was 700cc at the time of the interview, slugging it out with the new CB750 Hornet and MT-07.
The number of middle-class models equipped with parallel twin-cylinder engines has been increasing in recent years, such as Honda's CB750 Hornet and Yamaha's MT-07, which were unveiled for the first time on October 4.
Suzuki is competing in this market with a lineup centered on V-twin-cylinder engines, but there have been cases in the past where parallel two-cylinder engines have been developed.
That is the XE7, which was displayed as a reference exhibit at the 2015 Tokyo Motor Show, and its disclosed specs are a parallel two-cylinder intercooler turbo DOHC 4-valve. Its displacement and other details are not known, but it was said to be 700cc in our coverage at the time, so it would be in a class directly competing with the CB750 Hornet's 755cc and the MT-07's 688cc.
The XE7 was never actually released, but in 2019, Suzuki filed a patent application for a non-turbocharged naked model with a parallel two-cylinder engine similar to this one. One can infer from this trend that the XE7 continues to be developed as a naturally aspirated engine.
Although the patent drawings show only the framework, it is clear from the up handlebars, inverted forks, and suspension that appears to be 17-inch front and rear, that this is a naked sports vehicle. It is expected that Suzuki's new mid-size naked will be unveiled for the first time at the Milano show in November.
GSX-S750 [SUZUKI] Appeared in 2017 based on GSR750. It was equipped with Suzuki's traditional 750cc parallel 4-cylinder engine but announced the end of production in August this year. Is the parallel 2-cylinder Naked Sports the successor to this?
Suzuki's patent drawing of what appears to be a naturally aspirated version of the XE7. The frame appears to be a backbone type like the CB1000R. There are other drawings of a pipe frame + upright fork specification, but the style is the same naked sport.
This is a patent drawing of the XE7, with the silhouette of the Recursion itself. The silhouette is that of recursion, with the turbo and intercooler packed into the lath frame. It seems that XE7 was even tested at that time.
SUZUKI Recursion. The concept model was exhibited as a reference at the 2013 Tokyo Motor Show.
The engine is SOHC 588cc and different from XE7. It was not in actual working condition at this time.
XE7 is a phase-cranked parallel two-cylinder with a two-axis balancer
The turbocharged XE7 has a number of patents filed at the time it was exhibited at the Tokyo Motor Show in 2015, and its mechanism is now partially disclosed. A distinctive feature is that it is equipped with two balancers on the upper and lower axes, which is believed to significantly suppress engine vibrations.
The implementation of vibration countermeasures will allow the engine to be incorporated into the body package as a strength member, which will also reduce the frame weight. In addition, the drawings show that a phase crank is used, so it is likely to have the same 90-degree V-twin equivalent explosion spacing as the CB750 Hornet and MT-07.
Parallel two-cylinder engines of this type provide well-balanced power output characteristics, as in Yamaha's case, from the naked sport MT-07 to the adventure tourer Tenere 700 and the supersport YZF-R7. The new naked model, which is believed to be based on Suzuki's XE7, may show the same variation development.
On the left is the XE7 and on the right is the parallel two-cylinder engine mounted on the Naked Sport.
The left-side cam chain layout, clutch shaft installed on the left side, and other features are identical, suggesting that they are based on the XE7.
The XE7 patent drawing shows that two balancer shafts are placed above and below the front of the crankshaft.
A two-axis balancer is generally expected to suppress primary vibration and coupling vibration.
Front view of the crankshaft in the XE7 patent drawing. It is reasonable to assume that the pin position is in phase with 90 degrees since it can be seen that the pin position is in phase with neither 180 nor 360 degrees.