Easiest method is get an impact wrench with a 6 point socket and just rattle it off. If the opposite side engine cover is off you can use a flattened piece of copper tubing or a copper coin caught between primary gear and clutch gear. Sometimes putting transmission in 4th gear and having someone sit on bike to hold it on floor while you wrestle the flywheel rotor bolt off. Be sure to use a good tight fitting 6 point socket and steady pressure on a breaker bar. Best to use breaker bar to loosen before using ratchet. Anyone that's ever smashed their face or busted their knuckles on a slipping ratchet can easily explain the reasoning for using a breaker bar to loosen it first. Some rotors can be gripped with a plumber's strap wrench but too much pressure on rotor can break the matrix that cements the magnet inside and once the stuff fractures its game over. Needs new rotor. Will look for pictures and post if possible

 

Ah. Yeah. Forgot to mention you will need correct puller to remove flywheel once bolt is removed.

 

Very helpful as always Augie. Much appreciated. I watched a video and it seemed the guy (Rocky Mountain) was able to slide the rotor off by hand once the nut was removed. What kind of special puller is needed?

 

That removal was probably just a demonstration and rotor was previously removed and reinstalled loosely. They are a keyed fit on the tapered crankshaft and require a puller threaded onto internal rotor threads and will push rotor against the crankshaft and force the rotor off. I'm not in shop now. I will take picture when I get back and take picture of it.

 

Forgot I had a picture in my phone already. Flywheel/rotor pullers KTM on left. Universal 2 sided in center and Honda 4 stroke on right of picture. Be sure to purchase name brand tool. The cheap ones break easily

 

Worth every penny! As KTM threads etc are all metric it is easy to find one! But if you buy from one of the KTM suppliers you know you will get the right one.