The Yamaha YZ 125 has been a popular model for many years, as anyone can pick one up and have a blast riding it. A solid platform straight off the showroom floor, we decided to have Bill's Pipes go through the engine of the small-bore two-stroke in order to see what it's truly capable of. Jeff Springman ported and polished the cylinder, dropped in a high compression Wiseco single-ring race piston, over bored the carburetor, installed the new Moto Tassinari VForce4R reed block, and bolted on the Bill's Pipes MX2 expansion chamber and MX2 carbon fiber silencer combo.
