ADVANCE THE DEVELOPMENT USING “FRUSTRATION” AS A DRIVING FORCE

“Commercial motorcycles should not break down in a short time causing trouble to the customers. Thus, strength and durability are critically important,” says engine designer Suzuki. Testing engineer Ishigaki also says, “It was difficult to complete this motorcycle as a normal commercial model, because problems with functionality arose even after it received a certain level of positive feedback.”What can be felt from the development team’s comments is that there was no alternative but to repeat the steady effort of designing, test-riding and verifying. Tamura, who was in charge of the motorcycle’s fatigue and strength analysis, recalls his experience saying, “Whether a new motorcycle breaks down or not will come to light after the customer buys it. It takes a long period of time. We repeated tests again and again not to cause trouble to our customers. Because of a newly designed engine, it was a very challenging task.” Every time a problem arose, he reported it with evidence to the designing members, and then repeated tests while considering possible solutions. Each component was newly designed and their goals were set high. Nobody complained in words, but it’s easy to imagine that everything was a challenge to the limit. In fact, it was a repetition of designing, evaluating and breaking. Suzuki says, “I often found broken parts placed on my desk when I returned to the office. Whenever I saw such parts, I thought ‘Uh-oh, it’s over.’”

Each component was newly designed and their goals were set high. Nobody complained in words, but it’s easy to imagine that everything was a challenge to the limit. In fact, it was a repetition of designing, evaluating and breaking. Suzuki says, “I often found broken parts placed on my desk when I returned to the office. Whenever I saw such parts, I thought ‘Uh-oh, it’s over.’”

Then, we proposed a solution by the next morning in local time, taking advantage of the time difference. We repeated this process every day. As we had known the on-site situation to some extent, we were moving things forward by predicting what would be required, thinking ahead and taking action,” says Satoh. It can be easily imagined that what each member should have done synchronized well to arrive at optimal solutions by mutually exchanging thoughts and ideas together with their own experience and knowledge.
Of course, the team had to discuss with other departments in various occasions. In the case of examining the function and performance of cooling and fresh air introduction, after discussing with the creative center over and over again, they were finally able to refine not just the function, but also the exterior.

According to what we heard, there was no manufacturer in Japan that could produce the clutch complying with the specifications required by the development team, and there were only a few overseas. So they decided to try in-house production of the clutch. Although it was quite a challenge, they eventually succeeded in self-producing the clutch as an All-Yamaha technology with the cooperation of the drivetrain designers and employees of the Hamakita factory. It was a self-confident product that they describe as “our competitors would be definitely jealous of when disassembling the YZ450F.”

Not just the engine, but they also invested a substantial effort in the YZ’s symbolic aluminum bilateral beam frame. As they had received negative customer feedback about the previous model’s “stiff steering”, more than ten aluminum parts were fully refurbished. A number of changes were made to the frame; the main pipe was lowered by 15 mm to change the twisting position and the internal ribs and the engine suspension plate were newly designed. However, just the 15-mm reduction threw the vehicle body off balance during the development, making the motorcycle more sensitive to external disturbances in weight reduction. Furthermore, in order to achieve their goal, they also improved the vehicle body itself through trial and error, such as downsizing the air box. Although the team members enhanced step by step the operability including turning performance under such circumstances, everyone says that it was very difficult to find a middle ground for compromise.
“Motocross motorcycles are used in a wide variety of road conditions and environments. We had our test riders ride prototypes in various locations to gather their opinions. After their test-rides, we made changes to the frame such as drilling holes and shaving off the frame by a few tenths of a millimeter based on CT scan images. After all, there was no alternative but to test-ride and repeat modification,” says Satoh. This repetitive process of test-ride and adjustment by test riders and engineers results in higher sensory evaluation and easy operability, and eventually leads to excellent steering performance unique to Yamaha motorcycles. It’s not too much to say that the holes on the inward side of the frame for rigidity balance are the clearest proof of the team members’ struggle in their relentless pursuit.
Regarding the new YZ450F, which has been refined and completed as mentioned above, the development team says, “It’s an evolution that is completely different from what we have seen before.” They adopted mechanisms that create a sense of affinity with the motorcycle and enhance the user’s enjoyment, which are the tool-free adjustable front suspension, wide-range settings with the advanced special app Power Tuner as well as easy handling of the motorcycle itself.
What kind of evaluation did this motorcycle receive? In the US, where motocross motorcycles are extremely popular, Shootout and Press Test are held annually where new models are gathered together from all over the world so that top riders and media professionals thoroughly examine them. It is known that receiving the same positive feedback from the evaluators is quite difficult because these various riders generally give a variety of different remarks.
However, the YZ450F earned a lot of positive comments such as “compact,” “lightweight” and smooth” as the development team had expected. “Without leading the evaluators to give us positive feedback, we obtained consistent good evaluations,” says Ishino. It was a moment when the hard work of the development team members as well as many other colleagues and divisions involved were finally rewarded.
The evaluation results traveled around the world and orders for the YZ450F flooded in, quickly reaching the upper limit of the production plan. The 2023 race season will come into full swing soon. Let’s have great expectations for the success of the new motocross motorcycle that will lead the next generation.