I have a 1988 CR250 that I race in the bomber bike class in local harescrambles. Totally stock, except for handguards & pipe protector. Would like to have copies of Dirt Bike or Motocross Action tests, hop ups, or shootouts for this bike.
I raced a '88 CR250 back in '88 to '90). It was a raceable bike during those days with some hop-ups. I set stiffer fork springs (stock were soft), Boyesen reeds and Answer "Roost Boost". I definitely recommend the Roost Boost ( if You can find one). It made my CR to rev farther so You could stay on one gear a bit longer. I remember that I almost looped out the first time I tested it... You really could tell the difference.
Otherwise my CR was stock. I raced it for 3 years and nothing broke ever!
I have MXA shootout somewhere... I remember they said that fork springs were too soft and the powerband was "hang on and wait", torquey but not very responsive.