03 WR450 Bog on initial punch

[mikeswr450]

I have read other suggestions, but still have problem.Im running 170m, 48pj, #40 leak, 2-1/4 turns out.pro circuit exhaust & they reshaped the head.I have tried many jetting combos. nothing seems to help.Problem only when you nail the throttle.generally at 1500-2000'

[Chipstien]

Have you done the BK mod? If not, do it. ?

[mikeswr450]

Whats the BK mod?????

[RichieGoatGruff]

BK mod doesn't apply to to 03 or later models, YZ or WR...Yamaha changed the carb. See your manual about adjusting the accelerator pump...