engine portingHead Porting for Motocross Bikes and ATV's

Why should a motorcyclist invest money into porting their bike's cylinder head? Mass produced stock motorcycles have cylinder heads with generic port shapes. The rough angles left behind by the casting process hinder the performance of the engine, leaving horsepower on the table.

Should port work be included when installing larger pistons or high lift camshafts? Yes, it is very important to have the cylinder head upgraded as well. Remember the air pump analogy. A one-size larger piston will usually be OK, but anything larger will actually start choking the engine. The engine runs, but it is screaming for air. The larger bore cannot be filled with the current head setup. The head will have to come off and have larger valves installed and port work done to get the engine back to maximum efficiency. This is why you should talk to a professional before starting a project of this nature.

What are the different stages of port work? At Williams performance we have 3 levels of port work beginning with the recreational and continuing up to a Pro spec. The Recreational port work will remove all blemishes left behind by the factory casting. A pro am is basically the same as a recreational but is usually accompanied by larger valves on the stock valve seats with additional port work to match. A pro spec typically involves replacing the stock seats in order to install even larger valves. The Pro spec is an all out Pro port job.

What should I expect to pay to get my cylinder head ported? Depending upon the type of head, prices start at $300 and go up from there. All of our levels of port work include a competition valve job. We also will perform a thorough inspection of the head to check valves, springs and seals for wear.

valve portingIs there any advantage to having bigger valves if I port the cylinder head? Yes, to a certain degree, larger valves allow for additional port work, which increases airflow. Increased airflow equals more horsepower and a faster bike.

Cylinder head work at williams performance is done on the latest equipment. We have the facilities to completely rebuild all motorcycle heads. We provide state-of-the-art work with a short turn-around time so you won't miss a day at the track. Call Williams performane (352-206-0034) to get your cylinder head ported today - any make, any model. 3-5 day turn around. No down time. Complete cylinder head enhancement, services include:

Competition Valve Job: The most critical, high velocity flow around a valve is right at the valve seat. The competition valve job focuses on this area. The valve height is kept at a standard so you don't lose compression ratio. A competition valve job alone can yield approximately a 3% gain in horsepower. All Williams performance valve jobs are done on Newen contour bb CNC cylinder head machine.

Porting: Porting is by far the biggest single gain for a normally aspirated motor. All port jobs come with a competition valve job.

Valves and Valve Seats: To get more flow into a cylinder you can simply make the hole larger. This is accomplished by the installation of larger valves. We offer valves in a virtually limitless variety of sizes and materials

Designed for your application:Every cylinder head done by Williams's performance is tailored to the specific application. We take pride in are work and seeing that are customers receive the very best product they can buy. Give us a call for more details.


Engine Development

Williams Motors are designed to keep you up front, with the optimal combination of power and reliability, placing you consistently out front from holeshot to podium


Dyno Services

Nothing speaks the truth more than a dyno run, after all the modifications are done, it's time to reap the reward from the years of R&D Williams Performance has put into the development of ATV and Dirt Bike Motors

rider support

Rider Support

Looking for the next level of support? Williams Performance is always looking for the upcoming talent to fully take advantage of our work. Drop us a line and a resume if you want to join the team.