i havent done any carb mods or put my pipe on yet but i removed the smog stuff and capped all three holes (exhaust manifold, airbox, carburetor), since then after revving up and letting off throttle rpm's hold for a second and then come down, does anyone know if this problem will go away after i do the mods?

 

1.Sounds like you may have a small air leak. Make sure those caps are tight, especially the carb' one.
2. When you refitted the tank did you route the throttle cable correctly. Is it returning instantly. Could be a trapped throttle cable.

 

i never took the tank off, all i did so far is remove the emissions stuff, i checked all the caps and they're tight.

 

sticky throttle cable?

 

Saw something similar to this the other day on another forum members 07 KLX, the dealer did some adjustments to the carb to fix a hard start condition and the bike never ran right after he got it back (3 weeks later).
We tore into the carb and found that they had cut 5 coils of the slide return spring and left them tangled together with the spring, we also got the 7/64" drill it out to drill the slide but they had already done it but made the hole out to 5/32", installed a 115 main jet and turned the idle fuel screw out 3.5 turns (didn't know dealer was allowed to remove the anti-tamper cap).

 

no, i checked that too, its fine.

 

If it is not a binding throttle than it pretty much has to be either a vacuum leak or a slide that is not dropping properly when the throttle is relaxed (keep in mind that the slide is not connected to the throttle cable).

 

+ 1 on the slide.
Drilling the slide vacuum hole too large will cause the slide to "hover" momentarily when the throttle is closed, as will removing too many spring coils or a combination of both.
If the carb' is factory and untouched?
If someone has been in there and modded it (slide, vacuum hole) this could be the problem. Drilling the vacuum hole larger than 7/64" is a mistake. 5/32" is too large for the vacuum hole.
If it's a USA spec bike it should have a cap on the air/fuel screw. Easiest way to check if the carb has been adjusted. (no cap = adjusted ).
The OE spec for the USA carb is #118 main and #35 pilot.

 

nothing has been touched inside the carb, i bought the bike new, can the carb be capped where the hose for the smog pump comes off, or does that have to be able to breathe?

 

That little metal vacuum port on the top front of the carb that goes to the KCAS actuating valve must be capped off if the KCAS system is removed.