Wr450 dies when throttle is gunned after idling

[sjwr450]

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.

[5spoke]

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

[Indy_WR450]

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. ?

[sjwr450]

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.

[sjwr450]

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.

[RunAnywhere]

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