Anyone had there 17 + KTM 2stk do this?

Just had my friends '18 300XC apart after 80 hours. It had some similar lines in the cylinder, none you were able to feel with your finger/nail. His bike was still running perfectly, and really did not even need rings. Cylinder measured perfect, we hit it with some Scotch-Bright and put it back together....Running like a top.

Yes, my ‘18 250 SX had that at 1 hr. Found it when testing pipes and heads on the dyno. Couldn’t feel it, but we honed it and installed new rings. It didn’t affect dyno numbers.

Those marks I've seen on replated cylinders from the owner not cleaning the cylinder well enough of any debris from the honing job.

KTM owned it when it was originally honed...

Here is mine at 1 hr from new.

Very common

The BEST way to avoid (doesn't matter for performance) ive found is upon first fire up and break in - castor 927 - and essentially idled/hardly any rev for a while - and about 1 hour of super easy run time at 28:1


But new engines from OEMS (and ktm) are dyno run at the factory - and often if you break it down new it looks that way.

I KIND of believe some of it is due to not perfectly round cylinders because they aren't torque plate honed.

But it's not going to effect anything as shown - and after enough hours - the marks will go away (actually the whole cylinder slowly goes towards the marks look)

Here is my 2018 250xc at 5 hrs. I had my dealer look at the pics and they contacted KTM who told them it's normal. I didnt do anything to it and now have 19 hrs with no issues

Some 17 models had reeds break.

17 TC250 looked the same with 5 hours on it when I tore it apart to modify the head.

Normal, when hot things get egg shaped also you see spots like that. I'm not for the super lean ratios they recommend unless you are riding trails though.

Understanding oil migration times is good.

Harris up above is pretty close, but Idling with 927 is just going to start the carboning and gumming up process.
With top notch Synthetics having film strengths almost as good as castor.
Unless you're running high heat air cooled, (high RPM/high stress engines for extended periods like shifter karts or WFO for miles at a time, Castor is overkill.

Full disclaimer, Castor was what kept the old pre 80s air cooled engines from seizing unless they ran super loose clearances because Castor is and still the only oil that actually migrates TO hot spots instead of burning away.

Its also a dirty oil designed for race engines frequently tore down and rebuilt. I run Castor in our Karts, not in the bikes. Bikes can't burn it off, unless you are like a James Stewart on a 125 type. Then by all means...

my 18 tx300 and my 1 mile te300i - looked the same as yours OP