I only have one recipe that i have tried and tested! I am baking my first 2 tier cake and have to convert my recipe for a smaller tier. My recipe is for 10" and is: 450g SR flour, 150g plain flour, 440g caster sugar, 300g butter, 310ml milk, 6 eggs, 3 tsp vanilla essence. This size is cooked at 140C for 2hr 30 mins. I figured for smaller cake I would just make 2/3 batch and guess by height of batter in tin but then realised i have no idea how long to cook it!! Help! I have to make this cake tonight if possible!
Keep it all in proportion.
I tend to use the eggs as a starter to reduce the ingredient quantities. ie. 5 eggs is 5/6th of 6 eggs, so if you can work out 5/6th of all the other ingredients, 4 eggs is 4/6th of 6 eggs so reduce your quantities down to 4/6th of their original quantities, etc.
HTH!
Cheers!
.
I would cut everything either in half or by 1/3 so that you are using 2/3rd of the recipe like Candy said. You have the benefit of everything being in grams and you have enough eggs to do either one. Then Cook it at the same temperature, but I would start checking it after an hour. 2 1/2 hours for a cake is a LONG time to cook. But a six inch will definatly cook faster.
Good luck. I make smaller batches and stuff all the time and with everything converted to grams it is a TON easier.
I managed to cut the ingredients into 2/3 and just filled the tin up to where i guessed it should go - it was really about the timing. So far been in for an hour and 30 and i just keep checking and hoping for the best?! Ha! You must get over these silly questions from beginners! Does anyone have a great recipe that does not require so long to cook and can easily be applied to different sized pans - I would really appreciate it! 
Not knowing what SR flour is there and what is considered regular flour it is difficult to know what you need. Many of the cookbooks here in the US are not written in Grams. I actually take time and go through most of my cookbooks the first time I make a recipe and convert everything because I HATE it. I live in the US but love working in grams because it is SOOOOOO much easier. Hopefully someone can give you some great books that you can find there. But I do have the book called "Cake Bible", it is awesome. The lady who wrote it also has another book called Heavenly cakes. I have not made all the cakes but the ones I have tried I like and she converts everything to grams for you. If you know how to convert ingredients to grams (I love her book because she has a section that I use to convert other receipes) but there are lots of recipes on like. Here on CC there are many but Southern Living, Epicurious and lots and lots of blogs out there.
Sorry I can't help more, I am not used to trying to help others in other coutries because I don't know what you have availble nor do I know the textures you are looking for compared to what is traditional here in the US.
This is how I work mine out at home, if your recipe is for a 10", get a calculator and divide each of the ingredients by 10 then multiply each by the size of the pan you want to use say 8" = 360g SR flour, 120g Plain Flour, 352 castor sugar, 240g butter, 248ml milk, 5 eggs 2 1/2 tsp. vanilla essence. I would then start checking the cake after 1 hour, but I think going by your timing for the 10" it will probably take about 1 1/2 hours. HTH 
Quote by @%username% on %date%
%body%