New KDX Owner

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Jul 3, 2007
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#1
After some net searches, I need some help. I just purchased a 1999 KDX200. It's all stock except FMF Gnarly pipe and silencer. I ride mostly 1500-4000 feet above sea level. I am running Red Line oil 50:1, dissasembled and cleaned carb and air box. Here is my problem; runs good from low to 3/4 throttle but at WOT is sluggish and runs like the ckoke is on. I am also blowing oil out the exhaust. Jetting is stock, float level is good, new spark plug and looks clean, air filter clean. My next step is to clean the KIPS vavle and repack the silencer. Does anyone have any other suggestions?
Thanks.
 
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#2
Here is more info I forgot to mention. I live at about 500 feet above sea level and at home it idles good and runs at WOT pretty good. But at my favorite riding area, 2500-3500 above sea level, I have to turn in my idle screw all the way to get it to barely idle and experience the sluggish problem at WOT.
 
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#3
As you increase in altitude, the amount of oxygen in the air decreases so you will want to lean out the bike. You want the proper ratio of air to fuel, thus less air in the atmosphere correlates to needing less fuel going in. You need to jet the bike down, drop down 1 size on both the main jet and the pilot jet. Be sure to check the plug periodically to make sure the color on the plug looks good, brown to tan, to insure you are getting the proper mix. There may be others out there that can give you the right jet size for this altitude. What I have given you is the general theory for jetting for altitude.
 
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#4
Thanks for the advice. I am aware of atmosheric pressure at different altitudes. I am not disagreeing with trying a different jetting set-up, but my friend rides the same areas with his '98 KDX and is bone stock and has no problems whatsoever. Does having the FMF pipe on my bike make the difference in jetting between stock and custom?
 
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Jul 8, 2007
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#5
No Top End Fix

Hello I have had the same problem on my 89 KDX 200. On the end of the actuator shaft just behind the exhaust expansion chamber is a cover for the KIPS shaft. This houses the rod that moves the valve. Remove cover and check both inner and outer circlips are engaged. When the end clip comes off the shaft cannot move and you get no top end at all. However middle and bottom seem ok. Please check this as it was the problem with my bike.
 
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#6
You should have bought a KTM, they never have any problems! And if I were you Sally, I would learn how to twist the throttle like a man.
 
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#7
waftycrank racing said:
Hello I have had the same problem on my 89 KDX 200. On the end of the actuator shaft just behind the exhaust expansion chamber is a cover for the KIPS shaft. This houses the rod that moves the valve. Remove cover and check both inner and outer circlips are engaged. When the end clip comes off the shaft cannot move and you get no top end at all. However middle and bottom seem ok. Please check this as it was the problem with my bike.

Hi... do you know of anyplace on the web that shows pictures of these same parts you are describing in this inspection? This circumstance sounds similar to what I experienced on this '90 KDX 200 I recently bought and am in the process of rebuilding. I've got everything off right now, so it's the time to do these things.
 
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#9
firffighter said:
You should have bought a KTM, they never have any problems! And if I were you Sally, I would learn how to twist the throttle like a man.
What a twit!!
 
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#10
Come on. We all know that all KDX owners secretly want a KTM. Handsome ate my roost all last season.










Just kiddin'. Look at my signature. I sold the KTM and bought another KDX!
 
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#11
I was having this problem as well and when I pulled my jug I cleaned the KIPS as well and found that both of my exhaust valves were sheared in half and therefore they weren't opening at all robbing me of 95% of my top end. I then learned the E series 200's are notorious for eating those valves without good oil. I would start by checking those.
 
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#12
Latest update from my original problem. I did end up cleaning my KIPs and found that was the problem. It has run awesome ever since! If anyone has not done this yet, I highly recommend it. By the way firffighter, the only reason why you got rid of that orange P.O.S. and went back to team green was because you couldn't figure out why I was smokin ya through the trails! Orange bikes are for drama queens and models who ride "groomed" trails.


Except for David Knight, he's manly.
 
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#13
HandsomeRob said:
Latest update from my original problem. I did end up cleaning my KIPs and found that was the problem. It has run awesome ever since! If anyone has not done this yet, I highly recommend it. By the way firffighter, the only reason why you got rid of that orange P.O.S. and went back to team green was because you couldn't figure out why I was smokin ya through the trails! Orange bikes are for drama queens and models who ride "groomed" trails.


Except for David Knight, he's manly.

Good on ya! TEAM GREEN all the way :p