In a blender or food processor, puree the red peppers. Transfer the puree to a large saucepan. Add the sugar, vinegar, lemon juice and cayenne. Bring to a simmer over moderately high heat and stir until the sugar is dissolved, about 8 minutes. Reduce the heat to moderately low and simmer for 10 minutes, stirring occasionally. Remove from the heat and stir in the pectin. Bring to a boil and stir constantly for 1 minute. Pour the jam into 4 sterilized 8-ounce jars. Cover tightly and let cool for 45 minutes, then refrigerate.