Concerns about environmental protection and energy saving are growing in the world, and Thailand market also strongly requires an improvement of fuel consumption and emission for motorcycles. Therefore, we developed a 125 cm3 4-stroke engine with revolutionized fuel consumption and emission for Thailand market. For enhancing the fuel consumption, the friction of contact surfaces of rocker-arm and piston and the mechanical input of generator was reduced. Also the combustion efficiency was enhanced by changing the ignition timing by throttle opening. For reducing the emission, the secondary air pulse induction system, introducing fresh air into an exhaust port, was employed. As a result, the fuel consumption was enhanced 30% in ECE40 mode compared to the 108cm engine of previous model. The emission was reduced 55% in CO and 60% in HC+NOx against the value of the 4th emission regulation in Thailand.
Article of Honda R&D Technical Review Vol.15 No.1 (77 - 82)