Installing Harley Evolution Cylinders

Mike is moving right along with the assembly of this Harley-Davidson Evolution top end. The evolution cylinders have been cleaned and honed and cleaned again—first honed with a rigid hone and then finished with a ball hone. After a thorough cleaning, the walls of the evolution cylinders were covered with a light coating of fresh 20w-50 motor oil.

Before moving forward, Mike explains the importance of blocking the openings in the top of the crankcase with clean rags or paper towels. Debris, parts, or hardware can not be allowed to drop inside of the crankcase.

With crankcase and evolution cylinder gasket surfaces cleaned and prepped, Mike sets the front and rear base gaskets into position. It is better to install the gaskets now, prior to piston installation. The gaskets are installed correctly when properly aligned with the corresponding locating dowel pin on the crankcase top.

Mike slides four lengths of rubber hose over outer cylinder studs to protect the pistons and piston rings from possible marring during assembly. It is important to follow manufacturer instructions for piston orientation. An arrow on the top of the piston usually indicates forward or front of the motorcycle. This is an industry standard. The arrow will face the front of the motorcycle.

With piston rings already installed, Mike applies a light coating of oil on the wrist pin bushings and on the wrist pins. The front and rear pistons are positioned over their corresponding connecting rods. The wrist pins are then pushed into place and held into position with a circlip. A piston ring compressor and patience will be needed when installing the cylinders. It is not uncommon for assembly to take a few attempts. It is vitally important that piston rings are not bent or rolled during cylinder installation.

With the piston ring compressor installed, Mike squares up and aligns the piston & evolution cylinder. He slides the cylinders down over the pistons and pushes each cylinder down until mated against the base gaskets.

Next up, Mike will be installing the heads and demonstrating correct torque sequence.