Abstract:An original variable valve timing mechanism with two-mode intake timing parameters is developed according to the structural characteristics of small-medium displacement motorcycle engine. Based on cycle simulation, a cycle simulation model of VVT mechanism for motorcycle engine is created. The control strategy of variable valve timing and lifting running-model are carried out at idle speed low negative load, middle negative load, low speed high negative load and high speed high negative load. It has been proved that the performance of JH125 motorcycle engine can be effectively improved by loading the new type VVT system.