You really don't need a longer throttle cable if you think about it. With mine I rerouted it to go in front of the top triple clamp just behind the brake line and down the right side of the frame and cross back over in between to the carb. This keeps it out of the way just fine.
All 2-stroke pumpkinheads, with Scotts Stabilizers need to write down Vegli's advice. My billeted triple clamp was actually getting a groove worn into it from the throttle cable. This occured just since sept. when I put on the scotts.
I bought the '99 Honda CR250 cable (Motion Pro brand), and it works great!! It is a good 3-4" longer than stock. Part #: MP 02-247
Also the Motion Pro ODO cable from an older Yamaha is a cheap replacement for the EXC's stock odo cable #MP 05-0015.
After installing both, and both working well, I had to breath new life into this thread.