Here are the part numbers from Honda:
31190-PRA-000 idle pulley - $22.61
31175-PRA-000 idle pulley bracket - $39.96
31185-PCX-003 bearing cover - $5.14
90031-PRA-000 special flange bolt - $1.48
http://www.hondapartssource.com
and the belt size for this setup tends to be 50.5 inches long, 7 ribs. But your best bet is to take string and route it how the belt would sit, then use that length for the belt.