To make improvements in spark ignition engine fuel economy and emissions, a better fundamental understanding of the interaction between the in-cylinder flows and the combustion process is needed. The influence of in-cylinder flows on the natural gas combustion process in configurations representative of light duty vehicle spark ignition engines is investigated here. This investigation focuses on the influence of the mean and turbulent flow fields on the flame kernel development. The flow was characterised using two-component laser Doppler velocimetry and the mass burn rate was calculated from the measured in-cylinder pressure. Results from a single cylinder V6 production engine, modified to run on a single cylinder and to allow optical access, are reported. The discrete wavelet transform (DWT) is used to show the energy cascade process in the non-stationary engine flow field over crank degree and frequency. Specifically, the preferential breakup of vortex structures as the expansion stroke begins was observed. The DWT is also used to show how the flow field evolution influences the early stages of the natural gas combustion process. Turbulence scales smaller than 1.5 mm were found to increase the early mass burn rate. Larger scales were found to act as an energy source for the smaller scales, thereby indirectly influencing the combustion process.