2004 KX250F jetting help Power Now Mod?

Hey guys finally got my 2004 used bike all put together and looking real nice, but the thing is the bike isnt running real well at all. The carb has been taken apart several times and cleaned and has new jets in it 180main and 42 pilot in it. We got the bike running and fired up but it still has a good amount of popping. I have the needle on the 3rd clip down from the top currently and seems to be ok but the idle is pretty high i mean more that i would say is normal and its seems like as soon as we touch it to turn it down some it totally wont idle and will just idle down and sputter out. As for when we do hvae it running, I noticed it has some minor 1/4 throttle or so bogg off the bottom then pulls really nice midrange on up. I have heard about the Power Now mods? What are these all about and do they work well? Thanks any help is much appreciated

the power now that is installed on the airboot side of the carb, helps improve low- mid range power...wat it does it slices the single air venturi, in the carb into 2 smaller, faster, venturis, which u can see in any Power Now pic. The Power Plate assists the vacuum of the fast moving air by drawing the fastest moving air molecules through a positioned hole in the plate, (Powern Now Plate) increasing the speed of the top and bottom venturis entering the cylinder... it basically increases air velocity...give u more mid range power

but the Power now, i think is better than the PLus...

i would rejet with the increase air flow

I had both the Powernow and Powernow Plus in my 05 yz250F and liked them both alot and did not have to re-jet at all. With my 06 kx250F I have the powernow in it and like and I just last nite picked up a powernow Plus for really really cheep, new in package, under half off what it is suppose t cost, so just as soon as I get it, it will be in and I am sure as with my 05 Yz250F I will not have to re-jet. Never the less I think both work really well alone or together. I was able to ride a gear higher no problem with both in before on the 05.

Yea i might think of trying one of those. Made some more adjustments today but the bike still does not idle really. As soon as you take it off choke it idles high and slowly comes down and finally will just cut out and shut off abruptly.

Yea i might think of trying one of those. Made some more adjustments today but the bike still does not idle really. As soon as you take it off choke it idles high and slowly comes down and finally will just cut out and shut off abruptly.

first turn the fuel screw all the way in. Then turn the fuel screw out, allowing more fuel to pass, making it richer. I recommend going in quarter turn increments to fine-tune it. If the idle settles with more than 2.5 turns out with the fuel screw, u need a larger pilot. If the idle gets better with less then 1 turn out, u need a smaller pilot jet


i think u have a lean pilot circuit...check and see if it is plugged or blocked...and clean them out...also check the float height. The float height will effect the fuel going through the jets..

yea i just installed a brand new jet in it before i even started the bike 180 main jet and 42 pilot jet which we went up from a 40 pilot. The air screw i forget where my dad and I even agreed on setting it becuase it pretty much happens no matter what. As long as the idle is set high like seems like 4000 rpms it stays running but it thats no way to have it, as soon as we go to adjust the idle and turn it down a bit its like flipping a switch and the bike will slow the idle fine and then just idle right down and shut right off. We are searching all through the carb trying to find anything at all

Well, Finally got tired of dealing with the carb and my dad and I decided to take a look at the valves and certainly found the culprit. 3 of the valves were in spec and one intake valve was waay tight. But the bigger problem that we noticed was the timing marks were way off between the cams and the timing on the crank. The guy supposedly had just done them, but certainly had no clue what he was doing. So now alil shimming and some timing adjustments the bike should actually idle and start much easier.

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