There is nothing you are going to hurt pressure washing. If it is a gasser, cover the distribitor. Also check the chaincase covers are tight, they like to loosen up and you could get water in the chaincase.Yes it's ok to pressure wash your machine. In fact it is the only real way to get all of the grease and grime out. You may want to remove any access panels also. This helps with draining and also allows larger debris to escape.