Making Pear-Apple Jam

2 cups peeled, cored, and finely chopped pears
1 cup peeled, cored, and finely chopped apples
6- 1/2 cups sugar
1/4 tsp ground cinnamon
1/3 cup bottled lemon juice
6 oz liquid pectin

Crush apples and pears in a large saucepan and stir in cinnamon. Thoroughly mix sugar and lemon juice with fruits and bring to a boil over high heat, stirring constantly. Immediately stir in pectin. Bring to a full rolling boil and boil hard 1 minute, stirring constantly. Remove from heat, quickly skim off foam, and fill sterile jars leaving 1/4-inch headspace.