Application to 125cc motorcycle series (ex.HONDA 125)and also can be used of other similar model engines. Size structure: 1.Mix chamber diameter:Φ26 2.Mounting dimension:2-Φ6.5 3.Central moment: 48±0.1 Performance indicator 1.Max power: 7.5kw/8500r/min 2.Max turque: 8.3N.m/7500/min 3.Fuel economy: 2.0L/100km 4.Minmum steady speed:1500±150r/min