I test rode a 05 wr450 the other day. Between myself and the owner, we forgot to close the choke after it got warmed up. I noticed that fist gear felt, best way to describe it, as hesitant. I would almost bog a little till I got into 2nd, 3rd, etc... Would that happen with the choke open while riding? I also rode a 07 the same day and made sure the choke was closed. I did not notice it behaving like that at all. Very smooth, and from what I can tell, crisp and clean throttle response. Thanks for any help.