On my Versys 650 I tried it all ,started with a 1/2" drive and breaker bar with rear brake applied and in gear ,not a chance . Then tried a 1/2" drive windy gun...nada , then a borrowed professional 1/2 drive impact gun (usually used on working on trucks) ...... nope, a borrowed 3/4" drive windy gun and socket ....nope
Went through all the tools before ending up eventually with a 3/4 drive socket set on a breaker bar with a 6 foot length of scaffolding bar and the rear brake applied ,the bike in gear and a solid lump of wood through the spokes locking the wheel against the swinging arm , with a 15 stone plus mate on the end of the scaffie bar it cracked loose and then easily unscrewed.
When it cracked off I honestly thought the output shaft had snapped .