Then you are probably good if it starts good and runs good then it is good. Open exhausts are loud and grumblely and pop on occasion. It could be the throttle position sensor just unplug it from the wireing harness and leave the other part attached to the carb. If you remove it it can be a pain to reset it right.

I have no faith in human perfectability. I think that human exertion will have no appreciable effect upon humanity. Man is now only more active - not more happy - nor more wise, than he was 6000 years ago. Edgar Allan Poe