Motorcycle Repair: 96 Evo, kb pistons, fuel burns

Question
I have 10:1 KB pistons in my 80" '91 Ultra .. broke rod pin and gonna go back with 96". am told that lower ratio 8.5:1 max needed ... besides lenth of piston why the lower compression ratio?
or why lower the compression ratio?

Answer
On compression there is a give and take. The higher compression you have, the better the fuel burns, which in turn give you more horse power. The bad side is you need a higher octane fuel to stop pinging and the harder the bike is to start.
Not sure who told you to go with the lower compression, but for a 96 cubic inch that is a little low. The stock S&S motor runs 10-1 compression.
Good luck and happy riding
Mike