2003 KTM 125SX: $400 Craigslist Special

Man id be so pissed if i found all that in a bike i just got. Guess you cant expect anything less for $400. The guy clearly knew he done fucked up on the motor assembly

It's not too bad! Well, let me rephrase that lol. It's not unexpected.

I've got a bunch of parts that will fit your bike that you may be interested in. I've got cylinder heads, cranks that are in good shape, vforce reed cages, etc. Willing to let them go cheap as I have no use for them and would like to help out another member. Send me an email at samcam28@gmail.com If interested.

That would be AWESOME Sam, I'll get in touch with you right now.

At least you will have a decent bike when it's done, I had one of these and I remember it being a rocket.

I must say 400$ for that is a pretty great deal, for me at least here in ny. If I could find a bike like that for 400$ near me Id 110% grab it. deff a fun project. Looking forward to seeing the end result!

Sam here helped me out with all kinds of bits, hopefully getting a care package here at the end of the week!

I remember these bikes when they were new and they were lightning fast! There's also lots and lots of Ohlins and Trax PDS shocks knocking about, so you could even find one of those and work out a way of making it fit it your budget allows. Enjoy the build!

We all like to see a good rescue build....bring her back!

Goatsby wrote:

It's not too bad! Well, let me rephrase that lol. It's not unexpected.

Not to rain on the parade but looking at the pics, it seems like the intake port opposite from the exhaust is cracked on the top edge of it...better look closely at that

So looking at it I think you're right, that puts a bit of a damper on things. Here are some more pics, looks like a chunk is taken from the wall almost. Now that being said, should I spring for a 200 conversion if I'm going to have to replace this either way? I found a guy who has a 2016 200 cylinder with the complete power valve and he wants 400 shipped. I'd still need the crank and head.

Good luck, that seems solid for $400.

Cool bike! You could build a Langston replica out of it.

Sounds like a sweet deal!!

Man, it's weird what some people do with their bikes, isn't it? Like, did the bro leave the motor out in
in the rain disassembled or something? Tweakers!

JMX82, that's what I was thinking, that or either update the plastics style with a new airbox/subframe/tank. I'll have to be replacing due to someone cutting holes in them/ old age. Chip, that seems like exactly what happened lol. Someone left the bike outside with no head on.

Parts coming in:

Almost new 200 cylinder and head, 2016.
Brand new hot rods bottom end kit.
New Wiseco 200 piston kit.
A box of parts from a fellow VitalMX member.

Quickly running out of budget, but we'll make do!

If your going 200 route you HAVE to build it, loved mine

Looking forward to see how this goes

What kind of set up did you run on yours?

It seems that you already have radiator shrouds, front fender and front number plate from 2006 model. You could use subframe, airbox, seat and rear fender from a 2004-2006 model to complete the look. I think it's direct bolt on modification and was quite popular back In the day.

You're going to make it a 200??!!! Hell, yeah!!! It will RULE!
I have a 200EXC and it is friggin AWESOME. Perfect motor. You will love it!!

If you choose to go with newer style plastics you could build a Tyla Rattray replica.

I think this will be useful when you start rebuilding the engine Engine manual

That looks sweet JMX82. And thanks for the manual, I found the same one online, should definitely come in handy!

I got a package in, it looks nice. Just waiting on the new bottom end kit.

Waiting for more parts still, completely forgot about the transmission bearings as well, so those will get ordered today. Did this in the meantime! Waiting for it to cure a few days, and then going to wrap the high wear areas in a clear protective vinyl.

Hold on to that cylinder. It might be repairible. I had one that looked worse than that. Sent it to Ken O Konner Racing. He TIG welded it, machined it down then replated it. Looked brand new when I got it back.

I've gone up to a 200 bore so it won't be much use unfortunately. It's very clean though, same with the power valve. I'll probably have them up on ebay today.

A long awaited update! I got busy and couldn't put much work into the bike for a while but I'm back at it now.

New bottom end bits arrived, and the cases are sealed.



I was ready to put the whole engine back together today, and was quite surprised the previous owner's attempt at rebuilding the engine didn't result in any lost parts when...



The Driver Hub of the kickstarter is missing! I posted on a KTM specific board to see if anyone has that piece laying around who could give me some measurements. I'd like to make one today out of aluminum just to bypass waiting 2 weeks from the OEM supplier for a 3 dollar part to finish the engine.

Goatsby wrote:

Waiting for more parts still, completely forgot about the transmission bearings as well, so those will get ordered today. Did this in the meantime! Waiting for it to cure a few days, and then going to wrap the high wear areas in a clear protective vinyl.

What paint did you use? i have the same model bike im planning to frame up also

Sorry I just saw your post! I rattle canned it with krylon and primer. It looks good at 10 feet but there is orange peel. If I were to do it again I'd use an HLVP and sand blast it. If I wasn't a cheap bastard and would do it again I'd have it powdercoated. But it'll do.

Long time no update guys, was in the UK for a month staying with my girlfriend. Got back a week ago and starting to work on the bike again. This is the current state of things. A quick question on that note - is the reed cage gasket supposed to go between the case and the reed cage, or the reed cage and the carb boot? The gasket doesn't fit on the OEM cage case side, but does on an older V-force reed set I have. Tomorrow I'll hang the engine in the frame and do a compression test.