that ould be the goveror your right, search up types of small engine governers and see what you have.
mechanical goverors are a little tricky to disable. if you have the air vane type you are in luck.
sorry i wont broaden on the topic of how to make it gone, but i can tell you its a pretty simple thing.
4 strokes should have no problem with running wide open for a long trip, and by wide open i dont mean stuffed, i mean stable and fast.... any engine run wide open for a long time without a small break will blow up.
im pretty sure it has a little govrnor wire hooked up to the throttle assy. that backs it off
* i found a link for you, this should help. DONT overrev it.
Honda GX50 - MotoredBikes.com: Motorized Bicycle Forum