Unfortunately , the AMA guessed wrong on the displacements and four - strokes have now far outstripped the two - strokes they were trying to match .
In order to promote four - stroke engines the AMA gave them a massive displacement advantage .
Unfortunately , the AMA guessed wrong on the displacements and four - strokes have now far outstripped the two - strokes AMA were trying to match .
In order to promote four - stroke engines the AMA gave them a massive displacement advantage .