I put some 5" tri stars on the cat 350x but will have to add some thickness to the scrub brake pad, I'm sure it had a 6" rear and 5" fron originally or 6" on both but I am running the 5s, I have a rebuilt 2.5 flattie that has a 3/4 shaft and a pulse jet carb so it is a good one that runs super! It needs cleaning but that is it! I want to paint the minibike but dont really care about original colors so much I'm thinking blue or purple, and want to chrome the bars and bolt them on! I want to make a rider rather than restore it faithfully yet! There is time and I'm not doing anything that cannot easily be changed!