If it bothers you that much do something. Plant some trees. After all they are the atmosphere's air filter an we keep cutting them down. Run Amsoil synthetic oil at 100:1 and keep your bike well tuned. Ride a bicycle to work to help offset the emissions from the dirt bike. There are things you can do. However you must do them.
If you're going to be crazy,you have to get paid for it or you'll get locked up.
Hunter S. Thompson