Many people, especially lighter folk, have found that the engine dies when they lean forward in the seat. This is more prone to happen when facing down a hill, or trying to observe FEL activity. One owner at least found that a 5-minute adjustment to the switch beneath the seat solved the problem. On some models the seat switch spring consists of two brass stampings. Removing just one of them will reduce the tendency of the seat to rise up, but do not remove both or you will defeat the safety mechanism completely. Adding some weight to the seat to take account of a light driver might also work. As a last resort, eat more.