A lot depends on what kind of changes have been made and weather a factory rep. gets involved.
I know a fellow that had a new eltra guilde classic that had the engine in it that they had oiling problems with,had two engines go.
He had put a trailer hitch on it,the dealer told him to take it off because if the factory rep. seen it he would void the warrenty.
At that time with that motor the factory rep. had to see the bike before the work could be done.