kz250 diaframe

i just got a 1980 kz 250 ltd. when i got it it was in a box. with in a few hours i was riding up the street. i have had problems with it starting. could not get over 45 mph. i found that there is a ripe in the carb diaframe. does anyone have an extra they would like to sell or know were i can get one cheap. i can not afford the $100 i found for them on the internet but want to ride it. is the ripe the problem or is there other factors i am missing?

the rip is your major problem also it is only a 250 4 stroke so don't expect alot out the bike maybe 75 80 miles an hour tops. also welcome aboard.