ok, just put a 39mm FCR on my 400 ex, and it ran good unless you nailed it, would pop and choke and die like none other. so I went to do the BK mod, and noticed that I couldnt even manually push the pump linkage, so I started playing wtih it and noticed that I had to pull it the other way to draw the linkage out and then when I let go it would spray, because the timing screw was so far out it would let the accelerator pump be depressed almost fully at idle. so I turned in the screw in all the way so that with the slide closed the pump would actually be primed and reay to fire. also drilled and tapped it for my bk mod screw. left this all the way out. put the carb back on the quad, started it up and revved it a few times to make sure the ap circuit was full of fuel. then shut it off, looked down the throat and nailed it and the timing was too quick, barely sprayed the beginning of the slide, so i backed the screw back out til it missed the slide. started it back up and just messed with my duration adj. screw I added and got it to run SO much better. I can nail it now no problem. still every now and then it I stab it from idle as fast as I can it coughs, but not usually. and if I BARELY bring it above idle and nail it its perfect every time. before it would run liek crap even if I nailed it form about 1/4 throttle.

the jetting is still off at 50/170 but I am tuning the carb tomorrow when I go riding for real.