Just finished up my 2000 YZ250, so I’m pulling this 2003 KX125 out of the shed. This one I plan on selling, so no fun graphics or anything like that, but I’ll get it tip top before I send it down the road.
I bought it for $1000 CAD (700 USD). The seller claims he did a top end, but dropped a circlip into the bottom end. He pulled the motor to shake it upside down, retrieved it, and finished the job. When he went to ride it, it would only shift into 1st and 2nd.
I figured that when he flipped the engine and shook it around, some part of the shift shaft/drum assembly must have came loose, or that he installed it incorrectly, so I figured it was worth the risk.
The bike has WC rad braces, and skid plate. Tag upper triples with oversized bar mounts, and a full PC pipe. 
I started by draining the fluids and pulling the clutch cover. You have to take the pipe off to disconnect the linkage arm, which is kind of annoying but not the end of the world.
Once I got the cover off, I tried shifting the bike again, and low and behold, it shifted through all of the gears just fine. The gasket used on the cover looked pretty cheap and suspect, so I’m going to order an OEM one to try. I think the cheap gasket is too thin and causing the case cover to bind on something.
The PO used permanent Loctite on the clutch basket nut, which leaked through onto the shaft between the inner hub and basket. I could not for the life of me get them off. I couldn’t believe what was happening. I thought I was crazy. I was able to use a generic puller I had around to very gently pull the inner hub off.
A very janky setup, but it worked!
The bike had been sitting all winter and wouldn’t start. I think I might know why.
Getting warm enough now that I can turn the water on and give a good bath before I go any further too.
Nice, loved that gen. 125. That seat looks pretty chopped, that year came with a couch! Looking forward to more.
Yeah I'm going to order a full replacement seat for it. Overall it's not in terrible shape. Brand new tires front and rear, newer handlebars etc. I should be able to make this thing quite nice for not too much money!
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Can’t believe I’ve had this thing for almost a year lol.
This was on the back burner for sure, but it’s almost done.
After I figured out the shifting issue, it would not start at all. I cleaned the carb, tossed a new plug in, but still nothing. I tested the compression and it was 80lbs…
I took the cylinder off and it had a basically new piston and the cylinder must have just been redone. What gives?
I checked the ring end gap and it was MASSIVE. Like almost a full millimetre. I’m not sure what the deal was, but I ordered a set of OEM rings and now we’re at a healthy 170lbs. Super weird.
My buddy gave me a set of plastics from a KX250 he bought years ago, so I tossed those on to save some money on a new set.
New seat is in the mail. Hopefully it’s not garbage, it was cheap!
I was the first person to service the shock! Isn’t that crazy for a 23 year old bike?
Check the bladder in the shock , it is probably porous by now.
Sold today for $2800. Roughly $1500 in profit.
Not the biggest fan of the Psychic aftermarket seat fitment, and the cover is paper thin too. Not bad for the price and much better than the old shaved seat.
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