I did the BK mod on my 01yZ426 last week. Went fine, the stock APJ squirt was 2.7 seconds. I used a videocam (30 frames per second made it easy to get it exact as 9 frames is 0.3 sec, just advance the VCR frame by frame). Resulted in a good improvement, once I went up on the main jet. I just tried to do my WR250F, but it was exactly 9 frames, 0.3 seconds. The squirt was a little late so I adjusted the timing screw. Kind of bummed because it has a bad bog I was hoping to get rid of. I tried to do my friends YZ250F, but his squirt was only 4 frames, a little over 0.1 sec. Whats the best thing to do to make the squirt longer, shorten the stop on the pump diaphram? His bogs pretty bad. I checked the diaphram and everything seemed fine.