Peel and halve pears; scoop out core. Place in a solution of 1/4 cup lemon juice in 4 cups water In a large saucepan, combine orange and pineapple juices, sugar and cinnamon stick. Bring to a boil and simmer 5 minutes. Drain pears; add to hot liquid; simmer 5 minutes. Remove from heat, add amaretto. Place section of cinnamon stick in each jar. Pack hot fruit snugly in jars; fill with boiling syrup to within 1/2 inch of top rim. Remove air bubbles. Readjust headspace. Apply lids and screwbands. Process 500 ml jars in boiling water canner 20 minutes. Premove jars from canner. Check seals when cool. Makes 4 pints.