17' KTM 250SXF 4T Engine Problems HELP

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11/26/2019 6:57 PM
Edited Date/Time: 11/26/2019 7:27 PM

So I have a 2016.5 KTM 250SXF with 67.5 hours on it. I have done about as much trouble shooting as I can....and I'd like to have an idea as to what is wrong before I take it to my local shop. Bit of a story so hang on....

It all started after a fresh piston installation and having Twisted Development tune my ECU. Took the bike out maybe twice to a local track putting maybe 5 hours on it between the two visits. On the third visit on a freshly groomed track, I entered a very soft turn and washed the front but I was able to get my foot out and slowly lowered the bike on the shift lever side. When I got the bike up and started it, I could hear a loud ticking in the engine. On the way back to my truck, the ticking got louder and the bike started to run out of power. Put the bike on a stand and got my helmet and gloves off and started the bike again with the loud ticking remaining - strange - so I rode around the pits and the bike then really started to run out of power until falling stalling. Trying to start the bike back up (electric start only) there was this terrible high pitch screeching sound - alright, done, time to go home.
Got the engine out and found pretty good marks on the cylinder wall so I replaced the cylinder wall and piston (again). Water pump and valves were checked and fresh oil and filter - on starting the bike it ran for about 10-15 seconds absolutely no odd sounds but then the bike stopped running. Tried to start the bike again but the screech came back and now the engine basically won't even start to turn over, starter just clicks. Checked the starter and it is okay, not burnt out, so basically the engine is seized? What would have caused the screeching and loss of power after gently laying the bike down?
I was never able to get my head near enough to the engine to find exactly where the screeching or ticking was coming from.


11/26/2019 7:46 PM

Check your oil pump. I don't know how your tip over would have had an effect, but when i was working in those it was common for the two oil pump gears behind the clutch basket to warp (or break) and stop turning the pump. On one, it warped because the plastic scavenge pump on the right side of the motor was too long and was causing drag.


11/26/2019 9:36 PM

Without experiencing it first hand its hard to say.

If your bike was coming into my garage to be repaired id almost say for sure cases are getting split and the problem will be found during disassembly and will go from there.

If im guessing. The debris from the first cylinder mishap worsened the other parts to cause the 2nd mishap. That debris is like sandpaper in the engine. Not good.