KDXRIDER.NET

I have a 2003 KDX 200 with stock engine (6hrs on very first New top end), Gnarly torque pipe, torque reeds, open airbox, OEM filter, OEM stock needle, 45 pilot and 155 main, air screw 2 turns out.

The carb is sqeaky clean as are the jets and airways. The fuel is fresh 93 octane mixed with Yamalube at 32:1.

I'm in Georgia and our temps this weekend were near 70 degrees. We took a stroll at a local offroad park and the bike runs well in the higher revs, but it will bog if you blip the throttle from idle. It also feels a bit weak in the middle. I tweaked the air screw from 1.5 - 2.5 with no noticeable improvements.

Any help?

Do I need to go leaner on the pilot and change to the CEL needle, OR ?

What does your plug tell you?

I haven't talked to my plug lately. ........ Just kidding. I haven't did a plug check yet. I'm don't have much confidence in my plug reading abliities (no joke).

Do a search on plug read or plug chop test, there is a great write up somewhere on this site. If you're not sure about you conclusion, post a pic of the chop plug for 2nd opinion
If I can do it, so can you

As stated above there are numerous jetting threads. But you must get the pilot circuit dialed in first. Turning the AS in all the way or nearly all the way i.e. 1/4 out, should cause an engine stumble. Backing it out should cause a stumble somewhere before 2 turns out. Beins you don't have a modified carb you shouldn't be at 2 turns out. It should be around 3/4 to 1 1/2 out. Use a clean plug gapped correctly and make sure the engine is warmed up. There are other things to consider but this is a start.

But you must get the pilot circuit dialed in first

Sorry, but you must jet the MAIN first, and can then fine-tune your pilot circuit.

The main would seem fine as it is running well on the top at WOT. I hate a bike that bogs when I'm ready to zip up a hill though. I'll be doing the 1/4 throttle chop this weekend. I'll go from there.

The plug will tell you how your main is running. I can ride wide open with a 150 or a 160 and not tell much difference... until I pull the plug.

Sooo, what would I need to determine the correct pilot and needle position?

This will tell you everything that you need to know....

http://www.kdxrider.net/forums/viewtopic.php?t=1156

Thanks!

I'm going to shot-gun this for you and recommend going one clip richer on your needle. My bike was doing the same thing; blip the throttle from a slow roll and it would almost die, it was bogging that much. One clip richer and BAM!! That did it.

Fuzzy, if you start with your main jet first you'll be chasing your ass around your elbow while you try to get the mid range sorted out. You go ahead and do it your way and I'll do it the most efficient way.

LMAO

The main does a little more than simply WOT, and must be set as a baseline before you can realistically fine-tune your transition circuits. Your pilot can be way off during main jet testing, and not effect anything. Setup your pilot, and then change two main jet sizes, and it WILL effect your pilot. In your defense, as long as the main isn't too lean or so sickly rich enough to totally dog the engine you won't notice it that much (as inda mentioned)...Just giving up power, and creating a dirty fire. You can in fact jet the pilot against whatever WOT A/F mixture your baselined against....to get good throttle response, BUT for a perfect tune it must be done in the order of main-pilot.

We're all glad you can jet your bike to your liking though....You can certainely do whatever you want...Not trying to be a **** like some....Just trying to help someone new to a slide bike carb learn the right way to do things.