400ex pop

[400exrules]

when its idleing and i stab the throttle it kinda pops and stumbles.....but if i have the throttle like 1/8 in, and stab it, it revvs up fine. so am i rich or lean and what jet is it?

[GPracer2500]

First thing is to make sure your pilot circuit is correct. If it's wrong then the condition you're describing will be worse than it otherwise would be. Turning up the idle speed a little can help too.

I say "otherwise would be" because it's very hard to eliminate the miss that often occurs when stabbing the throttle open from idle. It's a fundamental limitation of most carburator designs (hurry up fuel injection). The newer FCRs have special tuning features that address this problem.

I talked about this phenomenon in a little more detail in this thread (http://www.exriders.com/vbb/showthread.php?s=&postid=2322873#post2322873).

[ohsobad_chevy]

Yeah, 4 strokes will not have a very snappy throttle like a 2 stroke will. Even with the accelerator pump, they will not react that fast. Although, I dont think that you can do this on your carb, but in the crf450's, I do believe you can change the leak jet in the AP to help with throttle response. They say that if you make it a tiny bit bigger it makes a night and day difference in throttle response on a 4 stroke. I allready checked into changing mine (stock 400ex carb) and it can't be done :ermm: But when you get your jetting perfected, it will be pretty snappy Brrrrapp. ;)

[400exrules]

ok, i thought it was normal, but i was just wondering about it