14/07/2026
The verdict is in… and a lot of you called it. 👏
Many of you commented that this engine couldn’t possibly have been rebuilt. I agree.
Looking at what we found inside, there is simply no way a proper engine rebuild was carried out on this KTM 300 EXC TPI. Any competent mechanic would have spotted the condition of these parts long before the engine went back together.
But the bigger question is… why did it fail in the first place?
The biggest clue was inside the crankcases. They were packed with dirt and grit.
In my opinion, there’s only one realistic explanation for that amount of contamination… this engine has been run without an air filter, or without one that was doing its job.
Once dirt gets into a two-stroke engine, it doesn’t take long before the piston, cylinder and everything else starts paying the price.
This is exactly why air filter maintenance is one of the most important jobs on any off-road bike.
Did you guess it from the last video? Let me know if you got it right! 👇