If you take the governor off the 2.5hp engine you will not gain any performance on take-off (that's what you're really missing). It will only raise your rpm limit. That engine has a small connecting rod that will most likely break and blow your engine if you are able to rev it over 4200 rpm(downhill?). If you want more power on take-off and the ability to climb hills, Change the back sprocket to a larger one. It's your best bet with that engine.
Check the screw on the linkage under the air filter and make sure it's backed out for full throttle, or better yet just take it off. You'll see it limits the throttle for little kids.
