2003 Kx125 Motor Swop

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10/16/2018 1:04 PM

I come here to help solve all my moto related problems but I haven't found any other threads on this topic.

I recently blew up the crank on my 2003 kx 125 which caused heavy damage to the cylinder head which is now scrap but I think I also may have damaged the cases beyond repair. Before pulling the trigger to buy all the replacement parts I want to investigate the possibility of buying a complete engine from a different year like 01 or 04 and was curious if anyone had any info on whether or not that would actually work. I am open to all sorts of feed back on the best way to resurrect this fun ride!


10/16/2018 4:10 PM

Not 100% on this, but i think the 03 was a one off year. In reality you can look on a microfiche and compare part numbers.

In my opinion i dont see how an entire motor(fresh) would be cheaper than getting some cases off ebay or something. If it were me i would just get some used cases and have them vapor blasted so theyre like new.


10/17/2018 5:30 PM

While 03 was kind of a one-off year, it actually had much in common with the 04+ bikes. 02 and older were completely different bikes, both engine and chassis-wise.


10/19/2018 11:41 AM

2003, 2004, and 2005 should all interchange into the frame without issue.


Tomac and/or Anderson for 2020.....

10/20/2018 9:27 AM

Thanks all! I'm having a heck of a time finding some used 03 cases. I will post some pictures of my cases to see if you guys think they are repairable or trash, before pursuing 04/05 cases.... That would lead to more exhaust options though smile