There are also discussions posted on several Harley-Davidson owner group sites concerning idle variation problems on some 2008 models using TBW, most notably v-twinforum.com and hdforums.com, with the latter having a link to a service bulletin released by Harley-Davidson referring to a TBW problem. Several posts say that the throttle control problems occurred while the bikes were being ridden, rather than just at idle. Further, in the cases of claimed unintended acceleration in automobiles, throttle and engine management computers may have no direct “cause and affect” as to how they may operate should a control system get an errant control input. That it uses an electronic signal rather than cables, a system malfunction could conceivably result in a variety of unexpected control problems, simply because a triggering electrical short, open circuit, or component failure could cause an electronic hardware problem, a software error, or both. A bike may accelerate, go to idle, shut off, go into limp-home mode—any of a number of unexpected behaviors based on a wrong signal in an electronic engine management system.
Conclusion
In the engineering career field, there is a concept known as “elegance.” It refers to the idea that the more you strive to keep electronic systems and their software programming simple, the less likely that bugs or unintended outcomes will result. The idea of keeping motorcycle control systems simple is worth considering for this reason. Consider also that following the “KISS” principle here may also be a good idea due to the lower level of physical protection for the rider of a motorcycle, as opposed to a car. There is a logical connection between these two thoughts: if a throttle system were to malfunction causing unintended de- or acceleration, a resulting accident would certainly have a greater potential for serious physical injury on a motorcycle than in a car.
Technology with a proven track record of decades in use are logical additions to motorcycles, and while electronic fuel injection and ABS brakes are more complex systems (respectively) than carburetors and simpler hydraulic brakes, you get a lot for the trade off for the relatively small increase in complexity. ABS brake systems are generally passive systems, where their effect on motorcycle operation is secondary to the rider’s input. Not so the case in more complex engine management systems, and some consideration should be given to fully “working the bugs out” before applying these systems to a motorcycle.
Some thoughts to ponder: will there be high-mileage TBW motorcycles still around and usable in 20 years? 30 or 40? Will the cost of repair exceed the value, as is the case with many current buy it, drive it, junk it philosophies with automobiles? Planned obsolescence as it’s called; it’s seemingly designed into everything these days.
Please share your thoughts on this with us. Have you had any odd experiences or lack of control from a TBW system or expensive repairs? We’ll print some of the responses and opinions in an upcoming issue of Baggers. B