Allowing a journalist to ride a raw and unfinished prototype motorcycle is practically unheard of. Very few companies would risk this early exposure, especially with someone who will publish his opinions. It’s akin to a sculptor showing an art critic a block of marble and saying, “What do you think of my masterpiece so far?” So, getting the opportunity to ride Motus Motorcycle’s MST-R sport-tourer was a unique opportunity and helped me gain considerable insight not only into the Birmingham, Alabama-based company but also the possibilities in this modern age of computer-aided design and small-batch manufacturing.
Considering that this motorcycle was nothing more than a blot of ink on a cocktail napkin in 2008, the fact that I was riding a prototype of one was amazing. It’s not like Motus principals, designer Brian Case and company president Lee Conn, just took an existing powerplant and stuffed it into a known chassis and called it their own. Instead, they partnered with Katech, Inc. and Pratt & Miller Engineering, two highly regarded American companies, to develop an original concept. Katech designed and built the 90-degree, liquid-cooled, longitudinal-crankshaft, 1645cc V-Four engine. And Pratt & Miller (winners of multiple 24 Hours of Le Mans, Rolex 24 at Daytona and Sebring 12-hour events with Corvette race cars) used its extensive experience to, among other tasks, design the chassis.
Perhaps the most interesting design aspect of this engine is that instead of traditional port fuel-injection, it uses GDI (gasoline direct injection), which sprays fuel directly into the combustion chambers. A number of automobiles are now equipped with GDI, and many motorcycle companies have been testing it, but so far, no production bikes have used it. Part of what makes this technology possible in this application is that the engine’s rev limit is set at 8000 rpm; making GDI work in higher-rpm applications is difficult, we are told. Another reason we haven’t seen this technology trickle down from the automotive industry is that the requisite injectors, which have to spray fuel at exceptionally high pressure (290 to 1800 psi), are very expensive. Motus plans to test its GDI system back-to-back with a port-injection system to determine production viability.
I met with Case and Conn, who were in the middle of a round-trip, cross-country promotional/testing ride en route to Mazda Raceway Laguna Seca for the MotoGP races. After Brian Blades photographed the MST-R in our studio, Case went over the pre-flight checklist of procedures I would have to adhere to on the fully instrumented, data-recording prototype. Quite a few aspects of the bike’s performance are still being evaluated, tested and tweaked, since the earliest that Motus expects bikes to go into production is a year from now. I was asked not only to be aware of these issues but to also take them into consideration in my evaluation.
One of the first things I had to learn was the starting procedure. Because mapping for cold startup has not yet been written for the GDI system, the throttle needs to be cracked open very slightly until the engine is up to temp. Once warmed up, the V-Four settled into a nice idle that is intentionally set a bit high to compensate for the rudimentary mapping in the lower rev range. The engine has a 75-degree crankpin offset that results in an uneven firing order, creating a sound that can only be described as a pair of Ducati Twins coupled together. In other words, it sounds sweet!
I was warned that the bottom-end mapping, combined with a heavily sprung clutch, would make taking off from stops a bit tedious. I did stall a few times but quickly adapted as the day went on. Other items to be aware of included limited steering lock (which will be addressed), a prototype gearbox that’s a little stiff-shifting and suspension spring rates that are still under evaluation.
Overall, the injection system delivers a fairly rich mixture to help protect the few engines that currently exist, so the occasional puff of black smoke from the exhaust was nothing to worry about. After I came to terms with the heavy throttle spring and stiff clutch, there were very few surprises in store. Heading over twisty Ortega Highway, I tried to get a sense of how well the GDI functioned and soon realized that in its current state, the mapping is actually quite good. When I asked Case if this level of fuel-delivery refinement was a product of GDI or simply because the system was in a non-EPA-compliant state of tune, he said that they are already working toward compliance and feel that they should meet those requirements fairly easily, possibly without catalytic converters.
While rolling the throttle on and off through the twisties, I tried to upset the injection system and make it behave poorly; but except for a bit of jerky on-/off-throttle reaction caused by stiction in the heavy throttle mechanism, it performed quite well. I next tried to determine how it reacted at steady-state cruising, and once again, the fueling was composed, with very little sign of surging or hunting. If Motus can refine the critical bottom-end mapping just above idle and achieve this same level of refinement while meeting emissions requirements, the company will have achieved something monumental that a few bigger manufacturers still struggle with. But we’ll reserve final judgment until we can ride an actual production model.
Knowing that the Motus’s pushrod, two-valve-per cylinder powerplant has a lot of Chevrolet racing technology in its genes put an expectation of muscle-car-like torque in my head, and the MST-R didn’t disappoint; the V-Four’s two-valve design provides real-world grunt over a broad spread of rpm. During one part of our photo shoot, we were in a fancy equestrian neighborhood, so I regularly short-shifted into fourth gear to keep the sound emitting from a pair of Two Brothers Racing exhaust silencers at a reasonable level. In doing so, I discovered that the engine would eagerly and cleanly pull from below 2000 rpm. The torque curve feels flat and accessible almost anywhere, making shifting through the tight and positive gearbox more sport than necessity. Acceleration was brisk but so smooth as to be deceiving. The twin-counterbalanced engine also is very smooth; I felt just a touch of vibration through the footpegs and handgrips.
When Pratt & Miller designed the 4130 chrome-moly steel trellis frame and swingarm, they utilized the engine as a stressed member. The design is stiff but its simplicity eliminated the need for expensive tooling for aluminum die-castings and forgings. And the chassis components on the bike I rode are sourced from well-established suppliers—Öhlins suspension front and rear, Brembo Monobloc racing calipers and forged OZ wheels.
Once the road turned curvy, I took my time working up to speed, not knowing what to expect. But after a short period of familiarization, I found that the chassis handled beautifully, with light, neutral steering (26 degrees of rake, 4.25 in. of trail), plush but well-composed suspension and familiar, trusted braking. With a shorter (58-in.) wheelbase than any other sport-touring model on the market and a claimed dry weight that undercuts most bikes in the class by more than 100 pounds, the Motus felt more sportbike-like than tourer. Feedback from the front end was excellent, giving me the confidence to lean the bike into corners without hesitation. Mid-corner, the MST was stable and tracked predictably. The suspension was just a few clicks away from being ideal for my weight and preferences, which would also have provided a bit more ground clearance, since I did drag the footpegs quite a few times.
When asked what they ultimately wanted this bike to be, both Case and Conn replied that the goal was to build a really fun sport-touring machine that leaned heavily toward the sporting side and away from the heavy, more touring-oriented offerings currently on the market. They wanted something lighter that offered good performance but with an upright and comfortable seating position. Case said he was inspired by early sport-tourers like Ducati’s ST4S. After riding the bike, I can say that Motus has easily achieved that balance. The multi-position-adjustable bars were set at a comfy level, and overall ergonomics were relaxed with just a hint of sportiness.
At the end of the day, I walked away impressed. I was very surprised at how good the bike was in its prototype state. If Motus is capable of making the necessary refinements and can get the MST-R to pass emissions requirements while maintaining even the current level of fuel mapping, this will be one hell of a fun motorcycle.
Currently, Motus plans to start producing motorcycles in 2012, which, judging from my experience with the bike, doesn’t seem unrealistic. But lots of hurdles stand in its way, such as reliability testing, establishing a dealer network, creating a parts inventory, conducting service technician training and determining a realistic price based on the chosen components and injection system. But Motus isn’t trying to conquer Honda tomorrow; it’s just trying to earn a sliver of the sport-touring pie. And if its goals are kept realistic and its investors happy, Motus has a great chance to survive.