Yes fellows there is a break in period to this machine. If you have one after several hours you should take the piston out and wipe it off. There may be some dust from the break in that can slow the machine down. Also when you change the stroke length to the shorter stroke the machine will gain rpms just like a 10 speed bike. The closer the axis on the crank to center the faster the rpm, the further from center is much slower. Hence you want to use the 3.5 mm stroke for lining which is pretty quick at 9-10 volts and really fast at 11-12 volts. 12volts-8,000 rpms. When I chose the motor I looked at the rpms of the Rapier II motor which is up around 14,000 rpms @ 12 volts. Which is way to fast for tattooing and using the machine at 8 volts the Rapier II is running at 6-7000 rpms. I felt more torque less rpms the motor will last longer and push bigger needles. Any furthe questions email me at [email protected] Cary