Noise signals,vibration signals and crank angle signal of 152 QMI single cylinder engine were collected.The main distribution ranges of the single cylinder engine noise energy were calculated through spectrum analysis and wavelet transforms,using a module of the software LMS Test. Lab. The engine noise signals whose frequency does not change with speed resonance were screened out with order analysis and wavelet analysis. Then the signals were processed with wavelet analysis in angle domain. Considering the ...