KDXRIDER.NET

Hey guys I've started to go through the jetting process for a new to me bike. Here are the specs
2003 KDX 200
FMF Gnarly woods pipe
Boyesen 607 reeds.
Airbox lid is drilled out
148 MJ
42 PJ
Clip in third position
Riding area 5,000 - 9,000 feet, 75 degrees

I've checked the float height which was fine and bought new reeds.
I can alway start the bike 1st kick when cold without using the choke. My idle screw is screwed almost all the way in to keep it to idle.
When adjust the air screw I can't tell any change in idle speed. Only when I almost close the air screw will the bike quit. I've cleaned my carb and clean the pilot and main jets. Could it be that my idle screw is too high that I am using the needle jet/passage now? My thoughts are that my pilot jet is still too rich.

Anybody else have it where the air screw doesn't affect the idle screw? I've heard that if you are way off on the pilot jet (way too rich) that it won't affect it. What do you guys think? I'm thinking of dropping to a 40 or even a 38 Pj.

Your still To rich on the pilot. If the bike's not wanting to idle and the air screw does nothing.

So should i jump down to a 38 then?

Anybody else have an opinion?
I actually started with a 48 pilot but had no change in idle speed so I dropped it to 42. Seems crazy to go from 48 to 38 in a pilot jet.

I have never ridden higher than 1000ft and my 200 uses a 40 PJ. Considering how much higher up you are, a 38 doesnt seem unreasonable.

I would check some of the jetting threads and try to find someone that is closer to your elevation for a double check. But your engine does seem to be telling you it is getting too much gas.

I run a 38 pj in my 200.
Clip in 2nd pos.
148 main.
Altitude 3000-7000 ' at 40-85 degrees F.
You may wind up going leaner still!

Thanks for your help! I bought a 38 and 40 and will try them out tonight. I'm excited to see if it helps. I will let you all know.

Okay so i tried the 38 but still no change in idle speed with air screw! What could it be?
i tried slowing the idle as slow as i could go with the idle screw but still no change.
Is it a pretty drastic change in idle with the air screw. Maybe its so smal of change that i cant notice it?
help cause this is driving me nuts!

Also riding it around it still seems the same as when i had a 48 pilot in.

Its possible your jet block gasket is leaking. I've got a 250 and I run a 35. Anything is possible. The idle pick up is noticeable simular to your bike running out of fuel. And your idle screw will be backed way out. Instead of being almost all the way in.

It sounds like you're getting extra fuel from somewhere. One possible suspect is the jet block gasket, especially if the carb has ever been dipped. I would recommend another cleaning, but sound like you've done plenty of that. When you cleaned the pilot and mains did you remove them or just spray through them? If not removed I would suggest tearing the carb down and disassembling it to clean it thoroughly. I don't ride that far up (except maybe while paragliding) but would expect your bike to be jetted much leaner than what us sea level living folks see.

someone needs to post a pick of a jet block gasket. I had a carb doing the same thing , I had a spare and swapped them out problem gone BUT i still dont know what was wrong with the other one . Jet block gasket? Heck if i know .

Never mind just found a pick @ jets r us down at the bottom of the pwk page goolge jet block gasket and click on the pic on the right .

This is what you dont want yours looking like:

dam that's dirty dude

And the guy wondered why he couldn't get his bike to run right!

So I did what you guys suggested and got a new jet block gasket. My other one didn't look too bad though but I replaced it anyways.
Started it up and rode it around and can't tell much difference. I tried messing with the air screw but didn't change much. On the air screw if I am between 0 to 1 turns out the bike idles real slow and quits. However between 1 and 4 turns out it doesn't seem to make much of a different. It still even rides the same.
I then tried dropping my needle to position #2 (leaner) thinking that I might be just way too rich on the needle and that maybe it's affecting my pilot but it still rode the same!!! This jetting thing is driving me nuts cause I make all these changes but the bike seems to respond the same. The bike runs fine but I don't know what a correctly jetted kdx should be like.

I took out the spark plug and here is a pic. What do you guys think? So my current settings are
MJ 148
PJ 40
clip #2 (stock needle)
I'm tempted to just buy the JD jetting kit. Any input?

searle7 wrote:I'm tempted to just buy the JD jetting kit. Any input?

I would hold off on that for right now. His kit had 2 needles and several main jets, I dont recall there being any pilot jets. His custom needles where the best I had ever tried, but they wont help the fact your idle screw is almost all the way in and your AS isnt doing anything.

Any chance your float valve is leaking?

Tedh98 wrote:

searle7 wrote:I'm tempted to just buy the JD jetting kit. Any input?

I would hold off on that for right now. His kit had 2 needles and several main jets, I dont recall there being any pilot jets. His custom needles where the best I had ever tried, but they wont help the fact your idle screw is almost all the way in and your AS isnt doing anything.

Any chance your float valve is leaking?

I don't think my float valve is leaking... though I have no way to check. No fuel come from the overflow hose. Since going lower on my pilot and main I have been able to back out my idle screw which I guess is a good thing. Well my AS is doing something as the bike sputters and dies once I get within 1 turns and in.
I'm tempted to jump down to a 35 pilot and onto the 1st clip position (leanest) and see if I notice any changes.

I just had the same issue with the neighbor's Yamaha. It was difficult to diagnose,but wound up being the float needle valve. I would definitely try the leaner pilot, but I do not like running the needle in the 1st clip position. Most of our riding is "on the needle" and that is just too lean for me.