Another Hello From Texas, S.P.I.

Welcome Brad, glad you joined us.

Giver'er Watchguy and welcome to the forum. I used to work for an engineer that was still a Canadian citizen from the Toronto area. He still works here in the Phoenix area.
South Padre sounds like a great place to ride a motor bike.
You can probably get a throttle cable at a place that sells quads or scooters.
Take your old cable with you to ensure a good fit.
If all else fails, you can order a new throttle and cable combo on EBay.

you can make a throttle cable out of bike cables by making the end that go in the carb here is a sorry video of how. I'm shorting the cable on the video but you can make the cable by buying a set of cables from Walmart pick out the cable that will fit the throttle twist grip tube. a shifter cable should work good for this. pull the inner cable out of the outer cable decide how long of a cable you want then cut off the excess of the outer cable. lube up the inner cable and insert it back into the outer cable you should have a lot of extra inner cable stick out now follow the video and you will see how to make the end for the throttle. I make all my cables ends
if you run into a snag let me know.
http://motorbicycling.com/f39/norm-shortening-throttle-cable-9010.html