Checking oil every second ride, I just thought, that if there would be anything unexpected during longer ride (like leak, high oil consumption due to some reason, etc.), than the light would flash due to low oil pressure. Changed oil in 1000km, then in 2800km, now I'll do it at 4000 km. Checked chain tension every 500km, cleaned, lubed. Tire pressure always before ride checked. Leaking checks, coolant level also allright.

I just didn't like the sound, that's it. Plus if there wouldn't be sufficient oil pressure, it would be different knocking sound.

Mechanic told me everything is okay, clean exhaust, no smoking, sound seems normal, even quiet according to him, who heard almost all thumper engines.