Hi all, has anyone go a spare set of front & rear pistons they can quickly measure up please?

Just stripped and rebuilt the sliding pivots on both fronts, the pistons & seals are in need of replacement & I want to source some stainless ones, I believe this chappie may be able to sort me out...

http://cgi.ebay.co.uk/Honda-nissin-cali ... 500wt_1156