You made me look back in the post. Your headspeed depends on your engine. Short answer is: somewhere between 1700 and 2000, but without knowing which engine and gear ratio, it would be impossible to know.

As an example, my Raptor 50 can safely reach 2000rpm. But how did I reach that number?

The OS50Hyper produces it's max horsepower at 17,000rpm. My Raptor 50 has an 8.5 gear ratio (10 tooth pinion, and 85 tooth main gear) 17,000rpm divided by 8.5 equals 2000rpm. And that is the headspeed I use.

Rafael