I just put on a K&N filter, procircuit pipe, and dynojet kit. I followed the instuctions on jetting, it has the 180 main jet, and screw turned 2 times. I took it out today to see how it runs and it pops when i let go of the throttle. It also feels like it's going to die on me when i'm in second gear. It lugs and i have to give it more gas and play with the clutch. What do i need to correct this problem? Am I too lean or too rich? I haven't checked the spark plug cause it got late. Should i move up on my main jet or down, and to which jet? And also it doesn't idle as well as it did before I jet it. It'll turn off on me if i don't give it some gas. Eventually it'll idle well once it's been ran for awhile.

oh ya and i still whooped up on my buddies 400ex and z400. I got the z400 by about 4-5 car lenghts(not quad lenghts)he was stock though[img]i/expressions/face-icon-small-wink.gif[/img]

 

OK....I just went throught the same thing on mine....I'm gonna try and help ya here.

Is it the carb mount filter, or in the box??

You need to be using the dynojet needle, with the clip on the 3rd position. I would try at least a 185 main, possibly a 190. Air screw needs to be right around 3 turns out. You may also need to go to a 47.5 pilot jet, but some people don't find it necessary.

Once you get the needle and the air screw close to the right spot it will start to idle alot better. I'm pretty sure that the needle, air screw, and pilot jet affect the engine from 0-3000 RPM. You should be very close with the setup I mentioned......hope this helps!!!

Let us know how it goes.[img]i/expressions/face-icon-small-cool.gif[/img]

 

well i have the filter in the box and the needle is on the second notch, i'll try to putting a 185 main jet, turning the screw to 3 and putting the clamp on the third notch and see if that helps. Should i do all these at once or do them one at a time.

 

In your original post you said you turned the screw two times. Did you turn it two times more than what it already was, or two turns out from gently closed? BajaDS650 is right about the airscrew, you'll likely want it three turns out from gently closed. If you just turned it two more turns looser than it was from the factory, you're likely at 4.5 turns out which is waaay too much.

What brand of jets are you running, Mikuni or Dynojet? The Mikuni jets are larger than the Dynojets so a 180 Mikuni might be too much fuel. There is nothing wrong with the Mikuni jets, just realize they are not the same size as the dynojets even though the numbers are the same. The link below is a chart which shows the differences in the size of the jets, it's excellent info to have.

http://home.swbell.net/tharthun/home/mainjets.htm

Basically go with what BajaDS650 said and be sure to ge the air screw set right first. (it's also the easiest thing as long as you are sure to set it from the point where it gently stops.)

 

Make each change one at a time, then look for differences. Give it a few minutes of running time each change to really look for differences unless the difference is night and day.

 

before my motor mods I ran dyno jet needle third clip with 190 jet lidless and a pro ciruit it ran great and there right about the air screw

 

The easyest way IMO to set the air screw is to (while its running), turn it to one side untill it starts to miss, then start doing it in the other direction (count how meny turns) untill it starts to miss again, then set it exactly in the middle.

Btw, i had more or less the same problem and it turnd out to be electrical, so dont get frustrated if u cant fix it with jeting changes, jast take it to the dealer and he fix it for you.

 

Bomrider's technique on setting the idle mixture screw is the way to go.
Typically, popping after throttle release is a sympom of too rich on the idle mixture screw - it may just be out too far.

 

Hightower, actually, i think i heard that from you

 

once when i changed the needle i didn't get the rubber diafram line up right and that made for a lot of bad running, so you might check that.