How to Upgrade a Harley-Davidson Stage 1 Motor

Written by bobby parker
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How to Upgrade a Harley-Davidson Stage 1 Motor
The motor is the heart of your motorcycle; upgrading it will revolutionise your ride. (motorcycle image by Greg Pickens from

If you own a Harley, you may start wondering how to make your own bike louder and faster. You've already gone through the steps to upgrade your motor to a Stage 1: You added a high-flow air intake system, as well as high performance mufflers. If you're hungry for even more pavement-crunching power, a Stage 2 upgrade is in your near future. Since Stage 2 upgrades include several variables to choose from, the amount of upgrading you complete is up to you.

Skill level:

Things you need

  • New cylinders
  • New camshaft
  • New clutch spring
  • New gaskets
  • Full range of mechanic's tools

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  1. 1

    Decide what kind of motor you want to build. When you delve into a Stage 2 motor, you no longer have the ability to simply bolt on components. Because you will be tearing the motor apart and replacing major internal components, it is important to know what you want the end result to be. Do you want high-end speed, or low-end torque improvements?

  2. 2

    Purchase the correct parts after you decide what you want your bike to do. You can either buy them through an aftermarket dealer, or go to your local Harley shop. If you buy your parts from a shop, you'll pay more, but you'll have the advantage of being able to speak to someone in person.

  3. 3

    Remove all of the old parts. For a Stage 2 upgrade, you'll be altering the cylinders and cam, at least. Begin the process by removing the parts currently on your motorcycle. Make sure that you organise the parts as you remove them to facilitate easy installation later. Clean all parts that will be reused.

  4. 4

    Machine the cylinders and other various parts. One of the quickest ways to improve power is to bore the cylinders. Make sure that if you bore the cylinders, you buy the correct size of replacement pistons. If you decided to purchase a Screaming Eagle Stage 2 kit, new cylinders are included. You might also consider completing other machine work, such as a valve job or a head job. These can be expensive, but they drastically improve the bike's performance.

  5. 5

    Install all of the new parts. After all the machine work is done, begin the process of putting the motor back together. Not only will you be installing improved cylinders, you'll also be installing new pistons, a new cam, clutch spring and gaskets. While not required, this is also a good time to consider installing new cam spacers.

Tips and warnings

  • One of the biggest decisions you have to make when you decide to upgrade to a Stage 2 motor is whether or not you will do the work yourself. If have a moderate to high amount of experience working on motorcycles, you should be fine. If, however, you are new to the field, consider having a professional do the work.
  • Evaluate the condition of your motorcycle. Before you can progress to a Stage 2 motor, it is important that your bike already be a Stage 1 motorcycle. This means that you should have already upgraded to a high flow air filter, as well as replacing the stock mufflers with high flow aftermarket mufflers. The basic idea of a Stage 1 motor is allowing more gas to get into the motor, while allowing more exhaust to get out. If you have not done these steps first, try them before proceeding.

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