Help! I pulled off and cleaned out the carb on my 07 KLX250S because it wouldn’t always start when cold just kill the battery. Now it starts and idles fine but it seems to be loading up with fuel, smokes black and cuts out when I apply throttle, especially at lower rpms. I had to change the plug it was black. I tried adjusting the air fuel mix screw, I tried it without the cleaner on thinking it might not be getting air but this didn’t help. The bike ran perfect before it was cleaned, it just started hard when cold. Getting too much fuel and loading up. Why?

 

You did not put the carb together right, take it out and fix it.

 

What didn’t I put in right

 

You probably lost the needle jet, therefore, didn't re-install it.. But there is other mistakes you could've made as well..

 

All of the components are in the carb including the jets, so?

 

... so, take it apart and fix it or take it to a kawa shop.

 

Man, you are so informative. Thanks for being so technical. Your advice is amazing. Tool

 

Your the tool that worked on your bike, now it doesn't run. You Happy?

 

Not as happy as when your sister visits. Get off my thread you idiot, you obviously have no knowledge

 

Carbs are pretty simple mechanical devices, so if there is something wrong, you can usually see it if you take it apart and look.

I'd definitely check the float, needle, and seat to see if they were installed properly and that the float level is set right and that the needle closes on the seat when the float is raised by hand.
I'd aso turn the idle air screw all the way in gently so as not to damage the delicate needle and turn it out one and a half turns just for a general reference point and see what happens.

Look at the brass jets and check them between an exploded diagram of your carb to see they are in their proper positions and not swapped.