There is a fine line to building an engine. If the limits are pushed too far (like many engine builders do) there are reliability issues. Pro Circuit’s goal is to give you the very best in high-performance service, without any loss of reliability. Pro Circuit engine modifications will give you increased power from bottom to top!
Pro Circuit has specialized in motor modifications since the early two-stroke Husky days. Our expertise in building the world’s most advanced engines is a direct result of working with the fastest and most talented racers. Riders like James Stewart, Ricky Carmichael, Ryan Villopoto and more have been a great help in our engine development process. In addition, every motor we build is thoroughly tested using our flow bench and race shop dynos.
From two-strokes to four-strokes, race bikes to ATV’s, almost any machine can benefit from Pro Circuit motor modifications.

Before you send in your motor, download and fill out this Service Form. Send it with your engine. A sales representative will call you once its received to go over the work you want done. Allow 7-10 business days for head modifications (turn-around time may vary, depending on parts in stock). Once your work is completed, your sales rep will call you go over billing and shipping if it has not already been discussed.