.....I have an 03 KFX W/ an HMF pipe and header. They called for a 170 main. A little too much I think. I went with a 155 suggested by some fellow duners. It runs fine except when it's about 70 degrees in the smaller dunes where there isn't as much air flow. I get a small flat spot just off the bottom. It makes a slight caugh ever so often. Once I get up and going at speed it behaves just fine. Do you think I may be just a hair lean? Causing a little starvation off the bottom?
.....Thanks guys.
-Spode.

Go to z400central.com, they have everything for the triplets, thats where I go for questions about my Z

is your airbox stock?(lid on or off....aftermarket filter?)

it sounds like your pilot jet may be lean...

Ok cool, here's a total list of what I did.

1). Installed HMF full system pipe and header.
2). Replaced stock main with a 155.
3). Removed the snorkle off the air box.

Everything else is stock.
Thanks a bunch guys!
-Spode.

Likely you won't be able to completely make that hesitation go away. Its the nature of that carb. I have been trying to get that out of mine, finally took it to a bike wrench and he wouldn't even touch it. Said thats just the way tose carbs are. I'm going to go to a Edlebrock or a FCR,can't decide.
good luck ,Steve

Did you try the 170? Give that a shot. They wouldn't steer you wrong I think.

I have a 03 and have a yosh complete alba k n filter set up and running with the air box lid off and running a 162.5 main 25 pilot with a 2.5 turns on the pilot screw ane I ordered the alba adjustable needle and it is set on the 3rd clip position.It runs great.I would either order a dyno jet kit and use there needle and jetting reccomendations they are pretty right on, also the stock needle in that carb is junk you can't adjust it up or down without 1mm shims to fine tune your bike.I orderd a dyno jet kit for the wifes bike and used what they recommened and it was right on. It sounds like you are running a little lean run it hard and pull your plug if it white you are lean the plug should be a light tan to brown color. the other way to do it is get jets in half increments and install inthl your bike burps then back off 1/2 jett size then fine tune with your needle.The dyno jett comes with a very good troubleshooting guide worth the money and rockey mountin atv has the cheepest price on that jet kit.have fun and a lot of trial and error but when you start getting clost it will pull hard and not fall off in power.

without spending any more money...

put the 170 back in with the stock needle and loose your air box lid.

if you want to spend a few bucks...

take a look here and pick up a few trinkets from alba.

Im running the stage III jetting set-up, K&N & Outerwear w/alba adaptor, no air box lid and a White Brothers R4 complete pipe.

(I also have the HotCams intake cam and the DRZ-E base gasket...but these mods did not change a thing on my jetting set-up.)

I have no hesitation at all. My only complaint is...im on the rev limiter instantly!!! Time for a Dyna ignition.