I have a 2002 kdx 200 bought new 1 year ago. Fouled alot of plugs with it(I counted 20 in garage the other day). Made jetting chages-155 main needle second from top, 42 pilot,AS 1 turn out, air box holes, still fouled plugs. Changed plug to a br7es and have not fouled one since(approx 7 months. Took it riding this week in a very large farm where I live and noticed this; bike has a slight bough at mid throttle as though running little lean on needle(this was in mid clip position). Checked #7 plug then and it was very dark brown as though it was running rich. Bike did produce alot of smoke as I was doing several high speed passes. I am running Mobil 1 mx2t at 40;1 temps at about 75 deg. I then moved clip on needle to second from bottom position and the bougging went away with a noticable snap to it. Can an old plug be causing this. How about KIPS system cleaning, havent done it since new. Thinking of a top end service soon. Just confussed a little, bike produced smoke with high speed passes and #7 plug was dark brown but it ran like it was running too lean with the hesitation a mid throttle roll on. Thanks for any input.
2002 kdx jetting
- Thread starter minidog
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canyncarvr
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- Oct 14, 1999
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Check this thread to get an idea of how different rider's plugs on the same bike on the same day look HUGELY different plug-color wise:
here
There is a lot more to plug reading than likely where you're looking for 'color'. Also, using a color indication to check a jetting condition when the riding is on-again/off-again (normal opening/closing of throttle) isn't productive because there are multiple overlapping circuits in the carb.
So...your plug can look 'rich' (again...unlikely the color you're looking at) and a particular circuit can be lean. That's likely the situation you were in.
Caused by a plug? No. KIPS? No. Not when a jetting change brought a performance change.
How did you arrive at 1-out on the AS? Is that the best throttle response spot? A too-rich AS gives you a flat spot right about where you're talking (AS effect runs up to just below 1/2 throttle). Not that anything is wrong with 1 turn out...but it's how you GOT there that's the point. Under slight load (say, uphill) from a slow walk speed in second gear, a quick-wick of the throttle to about 1/2 should show NO hesitation. Don't bother messing with it until your bike is well up to operating temperature.
Sounds like you're pretty close....just need to tweak it some.
here
There is a lot more to plug reading than likely where you're looking for 'color'. Also, using a color indication to check a jetting condition when the riding is on-again/off-again (normal opening/closing of throttle) isn't productive because there are multiple overlapping circuits in the carb.
So...your plug can look 'rich' (again...unlikely the color you're looking at) and a particular circuit can be lean. That's likely the situation you were in.
Caused by a plug? No. KIPS? No. Not when a jetting change brought a performance change.
How did you arrive at 1-out on the AS? Is that the best throttle response spot? A too-rich AS gives you a flat spot right about where you're talking (AS effect runs up to just below 1/2 throttle). Not that anything is wrong with 1 turn out...but it's how you GOT there that's the point. Under slight load (say, uphill) from a slow walk speed in second gear, a quick-wick of the throttle to about 1/2 should show NO hesitation. Don't bother messing with it until your bike is well up to operating temperature.
Sounds like you're pretty close....just need to tweak it some.
- Thread starter
- #3
I arrive at my air screw settings as follows; bring bike up to temperatue, then position throttle at about 1/8 throttle opening and hold there, then adjust air screw in till it stops (bike wants to cut off at this point)then start slowly turning out air screw out until I reach highest rpm-thats where I leave it. I believe that day in question that I didnt do this and maybe thats what happened. My problem is that I really dont have access to a wide open area to tune main jet. I read the post about color on plugs and found it be pretty interesting. Will buy some new #7 plugs (their cheap) and do some testing asap and will get back with you. Bike really respoded well to the needle change, with a noticeable boost in power. Fall is starting and temps. are getting cooler so perhaps this may be the problem. So the air screw has its effect from idle to 1/2 throttle opening? Perhaps this thing is more important than I thought. Im wondering if I should change needle back to mid clip position and tune air screw and see what happens.
canyncarvr
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Hi idle is a STARTING point for the AS...and hardly ever where it will stay.
Anecdotally speaking (and thus possibly of very little value I realize), my bike responds HUGE to a proper AS adjustment. 'Proper' in my case may well be 1/16 to 1/8 of a turn. 'Huge' in my case means a very obvious seat-of-the-pants increase in power. An RB carb mod exaggerates this circuit it seems (there are jet screen changes that increase the signal AT the jet block)..so I don't know that it is as critical in a standard carb.
But I DO know that hi-idle isn't where you want the AS. Adjust by throttle response (as noted in my first post). You'll find the AS 'in' a good bit from the hi idle setting.
I've read a good bit of, 'set it and forget it' idea concerning the AS. Big mistake! Well...if you want your bike to RUN that is!
Yes..the AS effect goes up to just below 1/2 throttle. Unfortunately...the clip postion, straight diameter, needle taper, throttle valve cut AND the main run in this same area!
You're familiar with the keihin throttle opening chart? Check CDave's site <http://justkdx.dirtrider.net>, click on <tech tips><carb tuning> for that graph. Also, note that recommended needle setting is #2, not #3 (#2 being where you started). It is possible (and pretty common) to MISadjust/set one circuit to make up for a separate MISadjust/set one.
In your case, a too lean AS can be 'compensated' for by a richer clip setting. Not 'correctly', of course.
BTW..don't let anyone TELL you how to jet. It's something peculiar to a particular bike/rider combo. That disclaimer said, you might try a 152. Certainly summer temps will tend toward a 152..and also if you have any aftermarket reed setup. Yeah...cooler temps coming on change that.
Keep after it, and you'll get it I'm sure. Your testing and the way your post reads says you're on the right track.
Another BTW...my 200: 40-152-BEL/2-#6TV. And that's too rich for a summer day. That's 38-150.
Have fun! That IS the point!!
Anecdotally speaking (and thus possibly of very little value I realize), my bike responds HUGE to a proper AS adjustment. 'Proper' in my case may well be 1/16 to 1/8 of a turn. 'Huge' in my case means a very obvious seat-of-the-pants increase in power. An RB carb mod exaggerates this circuit it seems (there are jet screen changes that increase the signal AT the jet block)..so I don't know that it is as critical in a standard carb.
But I DO know that hi-idle isn't where you want the AS. Adjust by throttle response (as noted in my first post). You'll find the AS 'in' a good bit from the hi idle setting.
I've read a good bit of, 'set it and forget it' idea concerning the AS. Big mistake! Well...if you want your bike to RUN that is!
Yes..the AS effect goes up to just below 1/2 throttle. Unfortunately...the clip postion, straight diameter, needle taper, throttle valve cut AND the main run in this same area!
You're familiar with the keihin throttle opening chart? Check CDave's site <http://justkdx.dirtrider.net>, click on <tech tips><carb tuning> for that graph. Also, note that recommended needle setting is #2, not #3 (#2 being where you started). It is possible (and pretty common) to MISadjust/set one circuit to make up for a separate MISadjust/set one.
In your case, a too lean AS can be 'compensated' for by a richer clip setting. Not 'correctly', of course.
BTW..don't let anyone TELL you how to jet. It's something peculiar to a particular bike/rider combo. That disclaimer said, you might try a 152. Certainly summer temps will tend toward a 152..and also if you have any aftermarket reed setup. Yeah...cooler temps coming on change that.
Keep after it, and you'll get it I'm sure. Your testing and the way your post reads says you're on the right track.
Another BTW...my 200: 40-152-BEL/2-#6TV. And that's too rich for a summer day. That's 38-150.
Have fun! That IS the point!!
XRDadKDXBeni
Member
- Aug 27, 2002
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How does the advice you are giving relate to the standard AS setting of 1 3/4 turns out or whatever the owner's manual specifies? Our 220 has always smoked a lot from day one, but it seems to run fine. I attributed the smoking to a 32:1 mixture of KLOTZ. Should we be doing some fine tuning on the AS?...which way, in or out? XRDad
canyncarvr
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- Oct 14, 1999
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The owner's manual isn't 'tuned' to get maximum performance from your bike.
Smoke isn't the issue I'm addressing. Your bike WILL smoke more if it's too rich...and if it hasn't been changed from the factory, it IS too rich.
The point is performance, not smoke. Rejetting correctly is about the single biggest bang for the buck you can get. It's just about FREE for starters. Besides, the knowledge gained about your bike will be of terrific benefit to you from summer to winter to elevation changing riding.
Which way? Check it as noted above, adjust for best response. If the quick-flick gets you a flat 'waaah' sound and a stumble, it's likely too lean, in which case, turn it in (richer). Turn it no more than 1/8 turn at a time, whichever way you're going.
Rule of thumb is, if you're out more'n two turns, you should put in a leaner (smaller) pilot. If your out LESS than 1/2 turn, put in a richer (larger) pilot. That applies to non-modified carbs.
1 3/4 may well WORK...but it's likely not an optimum setting.
Smoke isn't the issue I'm addressing. Your bike WILL smoke more if it's too rich...and if it hasn't been changed from the factory, it IS too rich.
The point is performance, not smoke. Rejetting correctly is about the single biggest bang for the buck you can get. It's just about FREE for starters. Besides, the knowledge gained about your bike will be of terrific benefit to you from summer to winter to elevation changing riding.
Which way? Check it as noted above, adjust for best response. If the quick-flick gets you a flat 'waaah' sound and a stumble, it's likely too lean, in which case, turn it in (richer). Turn it no more than 1/8 turn at a time, whichever way you're going.
Rule of thumb is, if you're out more'n two turns, you should put in a leaner (smaller) pilot. If your out LESS than 1/2 turn, put in a richer (larger) pilot. That applies to non-modified carbs.
1 3/4 may well WORK...but it's likely not an optimum setting.
XRDadKDXBeni
Member
- Aug 27, 2002
- 46
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canyncarvr: thanks for the helpful info...I am now rembering why I like four strokes so much! XRDad
canyncarvr
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- Oct 14, 1999
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Yeah...but with a 2-stroke-smoker you get to talk so much esoterical ethereal BS that everyone thinks you're magic! ;)
Well, or just plain full-of-it.
My eyes aren't brown yet, btw!!
heck...tuning a machine is fun! Much moh beddar for man-'n-'machine conjoinment.
repeat after me..........
we-r-one...ooohhhhmmmmm.....we-r-one...ooohhhmmmmmmm......
Cheers!
Well, or just plain full-of-it.
My eyes aren't brown yet, btw!!
heck...tuning a machine is fun! Much moh beddar for man-'n-'machine conjoinment.
repeat after me..........
we-r-one...ooohhhhmmmmm.....we-r-one...ooohhhmmmmmmm......
Cheers!
XRDadKDXBeni
Member
- Aug 27, 2002
- 46
- 0
esoteric...innate...yes, Grasshopper, we are one, as the ripples in the water are one with the pond. With a stroker you have more parts working for you, with a smoker, its less parts doing more. XRDad
canyncarvr
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- Oct 14, 1999
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:)... that's a typo? Prolly 'inane'...not innate!
Speaking of 'we-r...'
Got your WER, yet???
Speaking of 'we-r...'
Got your WER, yet???
- Thread starter
- #11
Tried needle in middle position today and tried adjusting A.S. and got pretty good results, but at mid throttle there was not a bog, but it just feels slightly flat to me. I am going back to needle in second from bottom slot, this is where I found a really noticable power difference. Just concerned this will make bike run a little rich. Anyone have any needle and throttle slide suggestions for a 2002 kdx-200 for 70 degree temps at no alltitude or humidity. Completely stock bike. Bike really had alot of zing to it when new and now it does pretty good but not like it was. Have a 155 main jet in it now with a 42 pilot jet. Have been experimenting with air screw alot but cant get results that Im looking for out of it.
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