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Recently, the electronic fuel injection systems have been widely applied to small motorcycles including scooters. In the high pressure fuel lines, plastic hoses have been increasingly used instead of conventional rubber hoses. As the plastic hose is less elastic than the rubber hose, the fuel pressure pulsates more in the plastic hose. To cope with this issue, we have conducted researches on how the fuel pressure pulsation in the plastic hose affects the accuracy of fuel injection. Keeping our eyes on the pulsation damping effects derived from the changes of volume due to the expansion and contraction of hose when the pressure changes, we have established the analysis method for optimization of the inner diameter and the thickness of the hose utilizing CAE analysis. The newly-developed plastic hose is applicable to motorcycles having a single cylinder 250 cm3 engine using an injector of a high static flow rate.

To reduce pain in buttocks while sitting on and riding a motorcycle over a long period, a 3D mesh cushion of thermoplastic elastomer (hereinafter referred to as “3D mesh cushion”) was used to develop a double layered seat cushion that would correspond to a cushioning action (the motion of the seat cushion, in response to impact from the road) and that would exhibit superior performance over time (deterioration of seat cushion). In addition, to clarify the differences in performance between the 3D mesh cushion and a conventional polyurethane foam cushion (hereinafter referred to as “foam cushion”), a ride comfort testing machine was fabricated to reproduce riding conditions, and evaluation methods were established for sensing the cushioning action of the seat in the low frequency range during comfort evaluation testing and for assessing seat cushion deterioration. The 3D mesh cushion and the foam cushion were compared using above-mentioned evaluation method.