How to Measure Evo Cam Gear with Pins

In this video, Mike teaches us the correct measuring procedure for correct Evo cam gear and pinion gear fitment. Harley Davidson produced the Evolution Big Twin motor from 1984 until 1999. The Evo was and is a very durable and versatile motor. There are still tens of thousands of Evolution Harley Davidsons on the road today.

When changing the camshaft on a Harley Davidson Evolution motor, it is very important to pay attention to Evo cam gear and pinion gear fitment. There are a few reasons for changing an Evolution motor camshaft. Camshaft lobes may be worn or damaged due to a catastrophic failure. Or, the most common reason for camshaft replacement is for improved performance. A camshaft is like the personality of a motor. A performance camshaft will boost horsepower as well as torque. Choose a low, mid, or high range cam depending on your riding style.

Choosing a bolt-in cam or a radical race cam will depend on your riding style as well as your budget. A stock Harley Davidson Evo cam gear and pinion gear have a precision fitment. These stock gears are also color coded. Harley designates a color for each size range. On a stock motor, you will be able to see a yellow, blue, red, green, or white mark on both gears. A replacement camshaft typically comes with a new gear already installed.

In most cases, this gear will be too large to run against a stock pinion gear. Even if the pinion gear is worn. If gear fitment is set up too tight, the engine will end up having an annoying, audible, whining sound that increases with rpm. If an Evo motor was running smoothly and quietly prior to disassembly, it is usually best to remove the stock Evo cam gear from the original cam and press it onto the new camshaft.

Prior to removal of the cam gear, it is very important to mark the gear where it fits over the notch in the camshaft. The gear will have to be pressed onto the new camshaft and be perfectly aligned with the notch in the new cam.

In some cases, both gears will need to be replaced. In this case, it is vital that precise measurements are made in order to purchase and install the correct size gears.

Watch the Full Evo Top End and Cam Video Project