This video shows a simple way to convert a gasoline engine such as lawn mowers and generators to natural gas.
This method, while effective, is not the best way to do this and provides no safety mechanism in case of a fault. Consider this method as a temporary method only to be used in an emergency situation. As this method provides no safety switch to shut off the gas flow in case of motor stoppage, I recommend that this method only be use in an outdoor environment and with continuous supervision.
This method will only work for gasoline engines that run at a constant speed, such as generators or lawn mowers. In the case of generators, that do run at a constant speed but require more fuel under heavier loads, you may have to adjust the gas flow to where the engine is running a little rich (too much gas) while idling so that there will be enough gas to compensate for the increased demand when the generator is placed under a load.