For 1.7 kg of fruit salad:

 * 400 g bananas (3)
 * 400 g apples (4)
 * 350 g kiwi (3)
 * 350 g orange (2)
 * 200 g lemon juice
 * 100 g sugar
 * 2*8 g vanillin sugar

In other words, mix bananas, apples, kiwi and oranges in a mass ratio of 8/8/7/7.
Prepare lemon juice & sugar mix with a mass ratio of 2/1 and one pack of vanillin sugar per 50g of sugar.
Add one fifth of the mass of the banana/applie/kiwi/orange mix as lemon juice&sugar mix.