Wr450 dies when throttle is gunned after idling

My '04 WR450 dies when throttle cranked after idling. It always has and now seems more touchy after installing JD jet kit. I'm running blue needle on 4th position (standard). #170 main jet. Zip-ty screw between 1 3/4 and 2 turns (it was at 2 stock). Bike has all the mods below. Since exhaust and grey wire mods it popped pretty bad on decel. Have not actually ran it with new kit, thought I would diagnose this first. If you let it idle and gun the throttle it dies, or gun the throttle a couple times in a row it dies. Any ideas? Sea level, 60 degrees today.

I had, and still have the same problem just because I haven't done anything yet, but I'm sure this would help.

bogging from idle

Adjust your squirt duration it is too long, as 5spoke gave you a link to that post. 165 main and red #4 or 5 may be a better choice as well. :)

The stock one was a 165 main. Although there is a S at the end. I'm going to mess with the accel pump settings and the fuel screw. I may change the needle next week.

Which needle is closest to stock blue or red? The bike ran pretty good stock, just the hesitation off idle and the popping on decel. I thought there might be a bit more on top (not that I needed it). I messed up my accel pump settings tonight, by not reading the manual correctly. Tomorrow I will adjust per the manual (with the rod) and then screw in a bit more.

I've had two major carb problems that had similar characteristics to your problem. The first time I had the infamous fall-on-its-face-off-idle incident, I hadn't messed with jetting at all. After too much time trouble shooting, it turned out to be the accel pump. Apparently it had sucked some trash in and plugged it. I installed a small inline filter. The last time is a bit embarassing. After rejetting and raising the needle, it popped terribly on decel and bogged under hard accel. Turns out I didn't screw the hot start jet back in all the way and it fell out completly. Amazing what happens when you quadruple the air mixture on the carb.

Good Luck

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