According to atvsport.com,72 mph
The KTM 500 has the the same bore as the 525. In EXC configuration (6-speed) with stock gearing it is good for 95 to 100 mph.
Depending on gearing upper 80's - 100 mph
Question is too vague, KTM 50 tops out around 50-52 mph while the 525 tops out between 90-100 mph.
110mph
90mph
The Top Speed Is Around 80 mph
60 mph
About 70mph
90mph
KTM recommends Motorex Top Speed 4T 15W50
With stock gearing top speed would be 50-52 mph.