it would help us out a lot if you listed what make, model and year of your bike...
is this a single style cable that provides open/closed with a spring effect involved to close the throttle / carb slide?
or
is this a dual style cable that one cable provides open and the other provides close?
typically speaking, either one installs using the same theory ... you would need to make all the adjustment settings to where it allows for the shortest cable to ease the installation. there is probably an adjustment up on the throttle housing on the handlebars, possibly an adjustment in the middle of the cable housing and possibly another down on the carbuerator itself ... these all need to be adjusted IN (shorten the length) ... these are to allow adjustments upon installation AND thru out the life of the cable as these can stretch some during normal life due to the stresses put on them.
if you can edit your question to include make, model and year, I will do a little more research on that specific bike and then come back and edit my response with more details that directly relate to your bike...
always willing to help when I have enough information to give a fairly accurate answer...