.028 - .032 or .7 mm - .8 mm
I have a 07 KTM 525 XCW and the manual call for 6mm on plug gap.
0.60mm
NGK BR8HS with a .032" (0.8mm) gap
0.7 mm
bad plug bad plug cap stator
NGK BR8ECM Standard with a 0.024 gap
yes there is the ktm ktm 85 ktm 110 ktm 125 ktm 150 ktm 250 ktm 500
You didn't specify what size but most dirt bikes will run a gap of 0.5-0.6 mm.
Impossible to answer, depends on what model KTM you have.
br9es, br9eg, br9egv, br9ev, rn2c, if it fould all the time something else is wrong
If you just bored it once or twice over, your stock spark plug will be all you need. A NGK BR10ECM (or corresponding plug from another brand) with a .032" (0.8mm) gap.
2009 KTM 250SX retail price $6598