▁to ▁its ▁ 2 5 0   cc ▁two - stroke ▁riv als . ▁It ▁benef ited ▁from ▁engine ▁compression ▁bra king , ▁which ▁allowed ▁the ▁engine ▁to ▁slow ▁the ▁bi ke ▁down ▁during ▁dec eler ation , ▁giving ▁the ▁bra kes ▁a ▁rest . ▁ ▁The ▁ 1 9 9 8 ▁Y Z 4 0 0 F ▁was ▁the ▁first ▁bi ke ▁to ▁come ▁stock ▁with ▁a ▁Ke ih in ▁FC R ▁car b ure tor . ▁ ▁In ▁ 1 9 9 8 , ▁Doug ▁Henry ▁won ▁the ▁A MA ▁National ▁Mot oc ross ▁Championship ▁ab o ard ▁the ▁Y Z F , ▁becoming ▁the ▁first ▁r ider ▁to ▁win ▁a ▁championship ▁on ▁a ▁four - stroke ▁motor cycle . ▁This ▁victory ▁is ▁considered ▁by ▁some ▁to ▁be ▁the ▁major ▁turning ▁point ▁in ▁the ▁mot oc ross ▁world — for ▁the ▁first ▁time , ▁four ▁stro kes ▁were ▁considered ▁a ▁compet itive ▁racing ▁machine . ▁ ▁Second ▁generation : ▁Y Z 4 2 6 F ▁ 2 0 0 1 – 2 0 0 2 ▁ ▁In ▁ 2 0 0 0 , ▁Yam aha ▁updated ▁the ▁Y Z 4 0 0 F , ▁increasing ▁the ▁disp lacement ▁to ▁ 4 2 6   cc ▁for ▁greater ▁power ▁and ▁thro tt le ▁response . ▁In ▁addition , ▁the ▁car b ure tor ▁and ▁j ets ▁were ▁updated ▁to ▁ease ▁the ▁Y Z 4 0 0 F ' s ▁starting ▁wo es . ▁ ▁The ▁next ▁year , ▁in ▁ 2 0