Does anyone know what this part is for

this is on a 1973 harley chopper,as far as i know its a 1000 or 1200 motor,this is on the right side case,it looks like a fitting for a speedo,but werent all the speedos of the earlier bikes on the front wheel,I am asking because this bike is a total custom and does not have a speedo and i want to add one.

if its a sportster motor its the tach drive

thanks

now for an even stupider question,what is the biggest sportster motor for 1973,im guessing mine is a 1200 but was told it was a 1400,is it possible to bore it out that big,if it is how do i tell if this was done,thanks

ok I just found a site that explains the vin stamped on the motor,and it says that it is a 1973 xlch 1000

is it possible to bore this out to 1400 or is this guy way off base,thanks

try The Sportster Home Page