It seems like no matter how much horsepower and torque your motorcycle puts to the ground, there is always some component in the motor that could benefit from a performance upgrade. It makes no difference what system of the motorcycle you are studying, there are inherent limitations based on any one of many factors. One factor is friction, which can show up in many different forms. No matter what causes the friction -- be it the bike moving through the air, tires against the pavement, or the internal friction created by the motor and transmission's parts rubbing against one another -- they all have the ability to hold you back.
1. Roller rockers may be installed...
1. Roller rockers may be installed on pretty much any motor, sitting in the frame without any problems. For photographic reasons, we installed these roller rockers from Crane Cams onto a 96-inch motor -- complete with Zippers heads -- as it sat on the bench. The first step was to install the new gasket and the lower rocker box.
By reducing friction, you not only free up some available horsepower, you also reduce wear -- in this case on the motor's parts. By doing so, you extend the life of these parts by staving off the debilitating effects tiny metal particles caused by wear have on your engine's oil.
One good way to beat this friction scenario is through the use of roller rockers. Stock rockers push directly on top of the valve stem, and through their movement, they drag across the top of the stem, causing both friction and excessive heat. By installing a set of Crane roller rockers, these forces can be greatly reduced.
 2. Next, the bolts were tightened,...  2. Next, the bolts were tightened, securing the lower rocker box to the head. |  3. It is apparent in this...  3. It is apparent in this photo what the major difference is between the stock rocker arm on the bottom and the roller rocker on the top. Instead of using the stock rocker to press directly on the valve stem, the Crane piece uses a small roller to actuate the valve's movement. |  4. Once finished, this simple...  4. Once finished, this simple modification will cause less wear on the tip of the valve stem. |
 5. The rocker shaft gives...  5. The rocker shaft gives the rocker arm a place to pivot from. Before the shaft was inserted into the rocker arm, it got a healthy dose of assembly lube. |  6. The prepped shaft was slid...  6. The prepped shaft was slid into the rocker arm support through the rocker arm and into the other side of the support. The shaft has a groove ground into one end of it. This groove needs to end up on the carb side of the motor, with the groove facing backwards. When the shaft was inserted all the way in, the groove lined up with the bolt hole. |  7. All of the bolts were then...  7. All of the bolts were then tightened and torqued. |
 8. The next step was to finish...  8. The next step was to finish assembling the rocker boxes. |  9. We then shortened our adjustable...  9. We then shortened our adjustable pushrods before we concealed them in the pushrod tubes. Then it was up into the head and down into the lifter block. |  10. From there it was just...  10. From there it was just a simple matter of adjusting the pushrods, and we were on our way. |