just bought a RPS Hawk 250 enduro. I Put A 37 tooth rear sprocket, 13T on front, New Chain. 2.87 ratio compaired to 3.33 factory. bike takes off well, and in 5th at 55 mph engine isn't screaming. replaced factory carb with adjustable PZ30 carb from
ebay. put in a NGK sparkplug, plug burns clean!!!! I have 27 miles on it still breaking it in.I have Rotella T6 5W40 in it. its JASO MA approved I recommend it.