02 kx 125

shaffstall721

shaffstall721

PR Member
My buddys got a 125 that seems to run fine sometimes, but i rode it the other day and when im at full throttle high RPMS it does like a spudder, it almost seems like a fuel cut off like a rev limited in a car but then it goes again. Its not at over rev either ide say about 3/4th of the way revved up. Its def. running rich i have no idea if that could be the problem or what, we just changed the top end (which it was doing this before that). Any ideas?
 
I no zero about adjusting carbs? Main jet leaned out a bit or? his plug is black as can be, and even has the oil spilling out the tailpipe. sorry im a newb when it comes to this my daddy used to do this for me lol
 
This is a total stab in the dark and may sound silly BUT... Put in a new plug. "Don't look at the old one or check it on the side of the head for spark", Just change it with a new one. PERIOD. Then let us know? If that fails try a new coil. The reason I say this is that the ignition could be failing (breaking down) at higher RPM's due to the advancing of the ignition timing. Will work fine at lower RPM's then fails when the demand for advancing the timing comes into play. JUST a SHOT.
Sometimes it is the simplest things we overlook.
 
1- drain the gas
2- install a fresh plug
3- put in new gas about 42:1 mix, I never run 32:1
let the bike warm up to operating temp, run it wide open through a field, pull the plug out right away, it should be a nice tan color. if its black use a smaller main jet, white use a bigger one.

if that dont work check your reeds make sure they are seating correctly and not broken. and maybe even a new ring/piston
 
okay so we changed the main jet, one setting leaner, and ran it full throttle like you said and the plug was WHITE, lol so we put the old one back in did just full throttle and it was fine, but for some reason it still has the studder, and it seems like a little bogg to me, its sluggish?hard to explain exactly, I am stumped. Its got a new piston and reeds. I am lost lol.
 
pilot? I thought wide open problems would be the main???

my guess would be the coil or ignition wire... look into an ibooster if you decide to replace
 
correct^ but I think last time I talked to corey (the OP) he said it was ok when it was like wide open but mostly studdering off bottom.. maybe im confusing him w/ someone else i talked to tho lol

but yes coil or ignition wire also would be sometihng to look into
 
Sounds to me like you need to move the needle clip. Try moving it up one notch in the needle.
 
Check all the wiring very carefully, and ground leads. Maybe even "temporarily" unplug the kill switch (just for testing purposes) to see if it is possibly faulty, (just put the bike in top gear and stall to shut it off). Don't forget to check the stator. The Bog could be secondary problem "loading up" due to the hidden problem.
Hope you get this figured out, and when you do, please let us know the answer.
 
PitRacer said:
Sounds to me like you need to move the needle clip. Try moving it up one notch in the needle.[/QUOTE
I second this pilot is out it only effects idle to 1/4 throttle needle does 1/4 to 3/4 and combo of needle and main are wide open. Also being it was so rich may want to repack silencer it could be all gumed up and causing some issues.
Click to expand...
 
his silencer definitely needs repacked.. i saw it its a mess lol

again i suggested pilot because the last time i saw him and the bike im pretty sure he said it was OK on top/wide open now but it was on bottom that it was having issues..
 
Iv had thus happen on a 125. I had a b8es spark plug in it. It needed a br9eg. Make sure you have the correct plug.
 
Thanks guys we are going to try all these one at a time lol so i can figure out exactly what it was, (Hopefully) and yes stacy is right when on TOP it seems to be okay, it boggs down low (RPMS) and middle, Not exactly full throttle or half, its confusing. but were going to try the pilot and then repacking, if that doesnt fix it the needle, and have the wiring and coil checked, which i have no idea how to do.
 
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