I've just been given a 84 Honda TRX 200 which probably hasn't been run for years. The first thing I noticed when trying to start it was that the thumb throttle is completely seized. I cannot push it in at all. Any ideas of how to troubleshoot this would be appreciated. I apologize but I am not a mechanic by any means.

 

Before assuming it's the cable, remove the seat and fuel tank and remove the cap from the top of the carburetor.
There will be a cable running into the center of this cap. After removing the cap, try pulling the slide out of it's bore. If it comes out, then you have a cable issue. if it doesn't come out, spray some penetrating oil in there and try working it free, but be careful not to scar the bore of the carb or bend the needle sticking out the bottom of it.

A carb slide can seize on new machines just sitting for a couple of months. They come in the shop all the time.

If the slide is not your problem, you are just out of $15 for a new throttle cable.....no biggie.