Motorcycles are not measured in amounts of horse power. The KTM SX65 2014 edition has a cc of 65. It has six speeds.
You did not specify what year, a 08 KTM 65 SX requires .5L 2002 sx65 to a 2008 sx65 according to my service manual only uses 300ml of gearbox oil. 2009 to 2011 uses 500ml of gearbox oil.
650cc of 10w30
250cc per fork
With stock gearing top speed would be 50-52 mph.
you compress the forks and fill it up until it is 110mm from the top rim of the fork tube.
125mm from the top edge of the fork without the spring and with the fork collapsed. Also the weight of the rider can change the oil height along with the riding style.
That's a matter of personal opinion. I actually have one of each, I ride the KTM most of the time now.
Possibly if gearing were changed. With stock gearing top speed would be 50-52 mph.
400cc 5wt fork oil
Fork oil level for a 2002 KTM 65 SX is 210 cc or 7.1 OZ per leg
240 ML of 5w fork oil.