When you properly care for your Harley bike, it’ll give you maximum service. One of the best ways to care for and improve your Harley Davidson bike (especially the Milwaukee – 8) is by installing the Harley breather bypass mod.
Wondering what a breather bypass is? I’ll tell you. Harley breather bypass is a modification made to the breather system of Harley Davidson bikes. It specializes in venting the crankcase pressure and blowby into the oil pan or a catch can instead of blowing it back into the throttle body.
In this article, we’ll delve more into the meaning of Harley breather bypass, what it does, and everything you need to know about it. So, let’s get started.
What is a Breather System and Its Purpose?
Before we move on to the breather bypass, let’s get a grasp of what a breather system is and what purpose it serves. A breather system is responsible for allowing gasses, oil, and pressure to escape from the engine crankcase and back to the air intake before the throttle body.
The reason is to let the engine burn the combustion gasses or pressure to reduce the emission of harmful substances rather than expelling them into the air.
However, models like the Milwaukee-8 have breathers that emit excess oil vapors. These vapors get sucked up by the throttle plate and then burned in the combustion chamber.
This causes large amounts of carbon build-up on the bike’s piston, hence disrupting airflow and increasing rough ride and overall poor performance.
What Is Harley Breather Bypass and What Does it Do?
A Harley breather bypass redirects the crankcase pressure and blowby gasses away from the internal breather system. Instead of recirculating these gasses back into the throttle body, the breather bypass vents them either into a catch can or the oil pan.
The main purpose of a breather bypass is to reduce carbon buildup inside the combustion chamber and other engine components. This is done by diverting blowby gasses away from the intake system. Also, the bypass helps prevent carbon deposits from forming on valves, pistons, and other internal parts.
You can do this modification by installing aftermarket breathers with an air filter. Also, you can do this by reconfiguring existing ones, like rerouting the breather hose to redirect the flow of gasses and pressure. The goal is to achieve better air circulation within the engine.
Why Do I Need A (Benefits Of ) Harley Breather Bypass?
There are several benefits to doing a breather bypass mod, including:
Reduced Oil Consumption
One of the main benefits of the Harley breather bypass mod is that it will reduce your engine’s oil consumption. So you will get more mileage at the same quantity of oil you have been using.
You can follow the Harley Fork Oil Capacity Chart to put the required oil on your bike.
Improved Engine Performance
When you install a breather bypass in your motorcycle, the engine will experience a better circulation of clean airflow. This potentially leads to improved combustion efficiency, better throttle response, and smoother acceleration.
Minimized Oil Contamination
A modified breather system will help prevent excessive oil buildup within the engine crankcase. This will reduce the chances of oil contamination and improve the engine’s health.
Reduced Carbon Buildup and Heat Buildup
The breather bypass mod reduces carbon buildup on the piston and inside the engine, thereby improving engine longevity. Also, it helps in dissipating excess heat generated during engine operation. Cooler engine temperatures contribute to extended engine life and more consistent performance.
Improved Engine Sound
Some riders in hdforums.com reported that when you install the breather bypass mod, it can improve the sound of the engine. This makes the riding experience more enjoyable and less prone to jerky movements.
Easy Installation
In case you don’t know, the breather bypass modification is designed to be a hassle-free upgrade. It effectively nullifies the internal breather system’s impact and still maintains the engine vacuum. This typically ensures a straightforward installation process.
Why Doesn’t a Harley Davidson Bike Come With a Breather Bypass From the Company?
Harley Davidson isn’t the only company using the same Harley breather system. For the past 25 years, most engines have manufactured cones with a breather system. Hence, Harley Davidson motorcycles do not come with a breather bypass from the company for several reasons:
First, modifying the breather system may void the manufacturer’s warranty and could potentially have legal implications. Harley Davidson, as a company, needs to ensure that its motorcycles comply with regulations and maintain the integrity of its products.
Furthermore, the internal breather system is designed to work in conjunction with the whole engine design and performance of the motorcycle. Altering this system could potentially affect the engine’s performance, fuel efficiency, and reliability.
Also, it brings about increased maintenance for riders. When you install it, it becomes another maintenance item, and most riders may not keep up with that. For example, some riders may not have the skills to change their coolant or brake fluid occasionally or drain their catch-can, leaving it to overfill.
The implication is that the engine of the motorcycle can get damaged, and that can trigger the riders to sue the company. So the company is ensuring to avert such occurrences that’ll most likely damage their reputation.
Again, Harley Davidson motorcycles are often seen as a blank canvas for riders to customize and personalize according to their preferences. So, the breather bypass mod is one such customization option that allows riders to optimize performance. Also, to address specific concerns related to carbon buildup and oil consumption.
Limitations of Breather Bypass Mod Installation
Installing a breather bypass has some limitations. First, it requires proper knowledge and understanding of the motorcycle’s engine system. Otherwise, a modification not done correctly will have negative consequences (like increased carbon build-up and reduced engine life).
Also, with the breather bypass mod installed, additional maintenance is required, such as periodically checking and emptying the catch can if one is used. Failure to do so makes the catch can overfill and get the engine damaged.
How to Install a Harley Breather Bypass on a Harley Davidson?
If you’re convinced enough to install a Harley breather bypass on your motorcycle, then follow the step-by-step guide below:
You’ll need these tools for the job:
- Drill and drill bits
- Barbs or banjo bolts
- Breather hoses
- Zip ties or clamps
Step 1. Remove the air cleaner and filter:
Start by removing the air cleaner and filter from your Harley Davidson motorcycle.
Step 2. Install banjo or barbs bolts:
Next, install barbs or banjo bolts onto the breather ports on the engine. These will serve as the connection points for the breather hoses.
Step 3. Connect hoses:
Connect breather hoses to the barbs or banjo bolts. Ensure a secure and tight connection.
Step 4. Route the hoses:
Route the breather hoses to a catch can or the oil pan. The catch can will collect any blowby gasses and prevent them from entering the throttle body.
Step 5. Secure the hoses:
Use zip ties or clamps to secure the breather hoses in place. Make sure they are not kinked or obstructed.
Step 6. Test and adjust:
Once everything is installed, start the motorcycle and check for any leaks or issues. Adjust the routing or connections if necessary.
Note that this process can be a tasking job to do, and it requires a couple of hours and some mechanical tools.
Cost Of Installing Harley Breather Bypass
As you consider this upgrade, keep in mind the potential impact on Harley Stage 1 upgrade cost. Here are some insights on the cost of installing a Harley breather bypass.
For a DIY installation, if you choose to install the breather bypass yourself, the cost can be relatively low. In fact, you can do it yourself for under $20, cheap, right? That’s why you need to give it a trial.
FAQs
Here are some questions people also ask about the Harley breather bypass and answers to them.
What causes oil to come out of a breather?
Oil comes out of the breather bypass when the crankcase is overfilled and when the oil fill gasket or oil fill cap is damaged. Also, a damaged or dirty breather system will let out oil.
What is the EPA regulation on breather bypass?
The U.S. Environmental Protection Agency (EPA) has regulations in place regarding the venting of crankcase gasses into the atmosphere. It states that it is typically illegal to vent crankcase or combustion gasses into the air.
Conclusion
Harley breather bypass helps maintain a cleaner and healthier engine by reducing carbon buildup and improving overall performance. It is a popular modification among Harley-Davidson enthusiasts looking to optimize their motorcycle’s performance and longevity. However, it’s important to note that modifying the breather system can have implications for emissions regulations and warranty coverage. Additionally, not all motorcycles may benefit equally from this modification, as the impact can vary based on the specific engine design and riding conditions.