Bike misses at when powerband kicks in.

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fatboyslim

Member
Apr 11, 2006
255
0
I have a 2000 KTM 125 SX. The problem is it bogs in first gear and all the otehr gears. It also missed a lot when the powerband kicks in. I just put a new top end in it and a new iridium spark plug. The bike has lots of spark too. There is also a lot of black sludge coming out of my silencer. The bike idles fine too. Please help! The weather here is really nice right now. I need to ride!
Thanks
 
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fatboyslim

Member
Apr 11, 2006
255
0
sorry but ya it hasn't changed. I did put the needle back down a spot and it helped a little bit with the sound but not really with the bottom end. Reeds, top end, carb and air filter are fine too still. I also replaced the my old spark plug with the type of spark plug the manual calls for. I just repacked my silencer. Could that be the problem if I pack ed it wrong. If unlikely I need more feedback.
 

sick 96 250

Damn Yankees
Member
Jul 16, 2004
1,207
0
Not quite sure then, whenever i had a bogging problem its was either the top end needed done, jetting was to lean or lean and rich in the wrong parts of the circuit or the air filter was shot, thats just my experience, i'm sure there are several others but i'm still guessing its withijn your jetting somewhere
 
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fatboyslim

Member
Apr 11, 2006
255
0
Could me not packing the silencer right be the problem, Because it missed terribly in the powerband. And the thing is I was out riding after I had repacked my silencer. The bike ran awsome until on like the 3rd day of riding I was pinnning it in third down a road and all od a sudden the bike lost power down low and up top. It's been that way ever since.
 

sick 96 250

Damn Yankees
Member
Jul 16, 2004
1,207
0
how long did you have it pinned? you know you cant hold a two stroke wide open for a long period of time right? You could of fried the top end already
 
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fatboyslim

Member
Apr 11, 2006
255
0
I held it open for like 5 or 6 seconds. And I already took the top end off to check my power valve (which was fine) and the piston and cylinder are fine. I'm thinking it might be either electrical or my silencer packing. What do you think?
 
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fatboyslim

Member
Apr 11, 2006
255
0
I took the carb into a KTM dealer and they said that the jetting and everything else was fine on it. I use 91 octane for fuel and I mix it with dominator amsoil at 40:1. Keep in mind that there is lots of black sludge coming out of the silencer.
 
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fatboyslim

Member
Apr 11, 2006
255
0
I think the you (the master) is right becuase I just got back from riding and when ever I pinned it it bogged and missed as well.
Is there any chance that it could be the packing though?
 

sick 96 250

Damn Yankees
Member
Jul 16, 2004
1,207
0
bro what are your jetting specs? Pull the carb and tell us what jets you have in there, what clip the needle is on and how many turns your air screw is out. And do not ride you bike anymore if its messed up, it will cost you in the long run.
 

Masterphil

DRN's Resident Lunatic
Member
Aug 3, 2004
1,003
0
Here's what we want to know:
Main jet size
Needle
Needle clip position (from the top)
Pilot jet
Air screw (# turns out)

Assuming that it isin't below freezing, and you live within 1000ft of sea level, this is a good baseline jetting to start with on a 125sx:
195 Main Jet
1469g needle
Needle clip 3rd position down from the top
48 Pilot jet
1.5 turns out on the air screw

Here is what I run if the temps are 70+ on a relatively normal pressure day, this setting is by no means "razor" sharp jetting, but it is quite crisp:
190 Main
1469g needle
2'nd position clip
45 pilot jet
1.5 turns out
 
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fatboyslim

Member
Apr 11, 2006
255
0
Jetting Specs for my bike:
175 main
R1467d needle
3'rd position clip
42 pilot
1.5 turns out (air screw)
 

Masterphil

DRN's Resident Lunatic
Member
Aug 3, 2004
1,003
0
Wow, your pilot circuit seems really lean. If I were you, I'd start out with a 195 main jet, 1469g needle on the 2'nd position, and put in a 48 pilot with the air screw at 1.5 turns out. I can tune for pretty much all conditions if I have a 190, 192, 195 main, and 45 and 48 pilot. I always keep the 1469g needle in the carb.

If you go over to KTMtalk.com, you will find a wealth of info on the KTM 125sx.
 
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fatboyslim

Member
Apr 11, 2006
255
0
The thing isit ran fine before I repacked my silencer and put the needle to the second position (which I moved back to the 3'rd). I don't think jetting can just go bad all of a sudden though.

I NEED ALL THE ADVICE I CAN GET!!!

thanks
 
Last edited:
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endofsilence808

Member
Dec 11, 2004
58
0
i had a problem like that on a 92cr125 a million years ago and it turned out to be a stator plate. dont know much of ktm but check your ignition. thats what i would do next. as far as the packing maybe you got some in the pipe it wraps around. just take it apart and check. it should be reuseable if its new. make sure your sliencer is not clogged. try changing gas maybe you have water in it.
 
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