KDXRIDER.NET

I bought my bike about a month ago, I've only ridden it one solid day and just an hour here or there. I remember back in the mid 80's being told that a KDX was more like a 4 stroke in comparison to powerband. That being said i didn't know what i should expect out of the bike. After reading on here and how to adjust your carb, i have been umm tinkering. From what i can see the bike is all stock.

Idle adjusting screw on the carb- doesn't seem to do much unless it's all the way in.

Air screw- the more i turn it out, the better my bike runs. Needless to say i ran out of screw.... The bike is just now starting to hit powerband. Apparently i never got it to kick in. The screw has to be out like 6 or 7 turns and ready to fall out. Now the bike kicks but boggs down in the middle(like starving for gas) and then opens niiiiiiice in the end of the gear.

From what i read, i should go down on the main jet? With the 6 or 7 turns, how many down? I live in Florida, Elevation here is 6 feet and 90degrees . The only thing done to the bike is the lid is removed. I ride in sand and mud(trying to go where the 4WD ATV's go)

Can someone start me in the right direction?

What year and model? Stock/mods? You've come to the right place!

You probably need to go down on the pilot and main.

What pilot and main are installed now?

It is an 89 KDX200. As far as the jets, i don't know. I am willing to bet they are stock. I will take apart the carb this evening.

Aside from this, the bike starts up hot or cold on the first kick.

Alright, i got the carb off and apart. The main jet is a 158. The slow jet is the one that's set down inside? If so i need to find a screw driver small enough to get at it. From the looks of it, it should be stock too. I'm willing to bet that these are original jets, therefor blown out a bit.

Here is a good place to start:
http://frpoffroad.com/kdxposed/engineTips.aspx

Once you have a starting point... this is a good read...

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

thanks guys, i just ordered a jet kit that goes from 150-160. I will then buy a 45 slow jet. Then it's all trial and error.

Just got my jets in.. Man that site is fast. Seeing that i had my air screw alllllllll the way out and it was getting better all the way. How many sizes down should i go? I was thinking 2 or 4. The kit has 150 152 154 156 158 160. I was trying to see if i could skip the 156 and go to the 154.

I was wrong on the jet sizes.. 150 152 155 158 160 . The 155 i think is too close, so i chose the 152. I put it in and got it all back together. It's too dark to ride right now( no headlight, i'm on that mission as we speak) I started it up and the bike sounds different. It sounds more "raspy". I went for a lil spin and got it into 2nd. Seems better already and i haven't fine tuned it yet.

The 'rasp" i am referring to, is that the sound of the reeds?

The raspy is proly the "close to tune" sound a bike get's when it is closer to being jetted correctly. Mine is very raspy....

m0rie is the king of the E series KDX's around here....

Then that's a good sign. It didn't rasp much at all before.

Most likely you'll end up with something close to a 152 main and 45 pilot with the stock needle. Look into getting a CGK needle and run it in the #2 clip to start with along with a 152 main and a 42 pilot.

m0rie wrote:Most likely you'll end up with something close to a 152 main and 45 pilot with the stock needle. Look into getting a CGK needle and run it in the #2 clip to start with along with a 152 main and a 42 pilot.

I'm on a 152 now and that's working good. I still have the 48 pilot in, it's boggy 1/4 to 1/2 throttle. I started messing with the idle screw, it's all the way in and cleared up as it went. The Needle is my next venture. Thanks for the info.

On a different note, when i ordered the pilot jet , i asked how much it was. The guy said 4.99. I was like umm ok while i'm here give me 2. Come to find out i bought two 5 packs of 45's . Guess i wont be running out anytime soon

m0rie wrote:Most likely you'll end up with something close to a 152 main and 45 pilot with the stock needle. Look into getting a CGK needle and run it in the #2 clip to start with along with a 152 main and a 42 pilot.

Well after almost 6 weeks of waiting i finally got my needle and jets. starting at #2 clip, is that from the top or from the bottom?

from the top,on the needle,

Keep this in mind 0-1/8 throttle is most effected by your pilot or slow jet, 1/8
to 3/4 is most effected by needle and clip position, 3/4 to WOT is effected by your main jet.

they do over lap and can be effected by the AIR screw setting. Idea setting
for the air screw or range should be from 3/4 turn out to 2 turns out it will go further, but thats a sure indicator of a need to make jet size change.

If temp, altitude and what many forget is humidity makes a difference.

the more humid it is as in Florida the more air the bike is going to need.

""""CAUTION DO NOT JET BY WHAT IS COMING OUT OF YOUR TAIL PIPE'''''


DO READ YOUR PLUG

TRY ONE CHANGE AT A TIME

TAKE TIME TO MARK YOUR THROTTLE FROM 0-1/8-1/4-1/2- 3/4- OPEN

USE TAPE AND A MARKER

TAKE A BREAK AND RIDE FOR FUN WHEN YOUR BRAIN HURTS

DO ALL THIS AT LEAST AFTER YOU HAVE RIDDEN THE BIKE FOR 20 MINUTES TO AN HOUR .

THAT IS ALL

I glimpsed through this..didn't see something pertinent to your initial observations.

The air screw (the brass one with a straight slot in it) being out more than a couple turns indicates the pilot is too large. The 'slow' circuit has too much fuel in it (pilot too large) and you are trying to 'fix' that situation by adjusting for more AIR than you can possibly put IN there.

Likewise/oppositely for the other end of adjustment. A too small pilot will want a small amount of air..and your airscrew being 'out' (for example) 1/4 turn will show that.

The jetting ranges krazy lists are correct..but there IS overlap that gets out of hand if the jetting is way off. If you're main is huge on the fat side (too big), you won't be able to effectively adjust the airscrew OR the idle screw (the black nylon screw).

It's not uncommon to have to go through a jetting sequence more than once. If your choice of method is top-to-bottom (main to pilot), after the initial run-through..you may still find a better running bike by doing it again.

It's about balance..a balance between the different circuits. That is what gives you a smooth power delivery thoughout the RPM range. A jet-set that is out of balance will give you big 'hits' when the circuit changes. That sort of performance may be fun for awhile, but it's no good for traction control and rideability.

The 'E' series (what you have) can lug and grunt with bikes MUCH bigger than their size. It is also common for them to have broken KIPS parts..the RH subvalve in particular. Trying to jet around THAT situation will drive you nuts.

It is also common for them to have broken KIPS parts..the RH subvalve in particular. Trying to jet around THAT situation will drive you nuts.

I 2nd that, thought I had a bog from idle to 1/2 throttle, and turned out my actuator was trashed

FTR...The 'H' model KIPS doesn't have the self-destructing pieces the 'E' does. Breakage in an 'H' is usually due to a maintenance error. 'E's just tend to...more often.

Smokey: Take care to discriminate between notes concerning 'H' and 'E' models. While similar in operation, the actual makeup of the parts is quite different.

canyncarvr wrote:FTR...The 'H' model KIPS doesn't have the self-destructing pieces the 'E' does. Breakage in an 'H' is usually due to a maintenance error. 'E's just tend to...more often.

Smokey: Take care to discriminate between notes concerning 'H' and 'E' models. While similar in operation, the actual makeup of the parts is quite different.

Thanks CC for the clarification, I tend to forget the H model is not the only one still running.
Learn sumthin everyday on this site

The 'bog' comment still fits regardless of model.

Point is (was..and I've done it often myself) when the subject IS 'E' bikes, references to things 'H' gets confusing.

That did get sorted out early on in this thread.....

Same with 'R' and 'SR' bikes.......