For 1.7 kg of fruit salad:

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.