I finally decided to install an external breather system on my Harley. My Street Glide doesn't have much blow by, however, the little I do have I don't want it going into the cylinders.
Why It's a Good Idea
You don't have to be mechanically minded to figure out why bypassing the breather vents on your Harley is a good idea. A simple google search will give you a very accurate description of why. Here are the results from google search on the topic.
"A catch can on a Harley-Davidson motorcycle is used to capture and separate oil, condensation, and other impurities from the crankcase vapors before they are recirculated back into the intake system. This helps keep the intake clean, potentially improving fuel economy, throttle response, and reducing carbon buildup on valves."
Well said Google AI!
Clean Intake
Catch cans prevent oil, condensation, and other byproducts of engine combustion from entering the intake system. This can help prevent the buildup of deposits on intake valves and other components.
Improved Performance
By keeping the intake clean, catch cans can contribute to better airflow and combustion, potentially leading to improved throttle response and fuel efficiency.
Reduced Detonation and Knocks
Catch cans can help prevent the re-entry of hot, oily gases into the intake, which can reduce the risk of detonation and knocking.
Reduced Engine Wear and Longer Engine Life
By keeping the intake cleaner, catch cans can help reduce wear and tear on various engine components. A clean intake can contribute to a longer lifespan for the engine.
Basic Maintenance
Periodically you will have to check the catch can or filter for oil buildup. It's really easy to just empty and clean the catch can or filter at every oil change as part of your routine maintenance. The long term results for you Harley are worth it.
Installing a Catch Can or Filter
Different years of Harleys may require different routing of the hoses. Before drilling anything, figure out what might be in the way before hand. You will want to inspect behind the air filter thoroughly for anything that may cause an obstruction that might not allow the tubing to pass through.
Catch Can or Filter
Either one will suffice for bypass venting. Older Harleys would vent the oil straight onto the road without either. Then the EPA got involved and told them venting oil onto the road, thus into the environment, wouldn't fly anymore and made them come up with a solution. That solution was venting blow by into the cylinders to be burned up with the fuel and air mixture and spit out of the exhaust. This appeased the EPA but now caused buildup over time on the piston head that is counterproductive to the engines operation and longevity.
Is It Legal
This question will have to be addressed by the state or county where you live. For instance, I live in a remote area of Texas and am not required to have a vehicle inspection to get my tags every year. If I lived in a major city in Texas inspections are still required. An inspector might not pass the motorcycle. I wouldn't see any issue if the oil is contained in a catch can or filter, but you wouldn't want to have it draining on the pavement under the bike for an inspector to see.
You might also have an issue if you get pulled over out of state. Law enforcement might ticket you if they know enough about external venting and understand what they see. I assume it would be like states that have a noise DB limit and will push a broomstick up the tailpipe to check for baffles and cats. This is something you need to research for yourself and decide if its worth the possible confrontation.
Installation Media
Below is my video of how I installed my external breather tubes and filter. I also included links to the parts that I ordered on Amazon.
¼" 6mm Hose Barb Tee T Fitting Adapter Aluminum Black- https://amzn.to/4kCuSmL
High Performance 12mm Air Filter Vent Carburetor Cleaner Breather for
universal fit for Custom Assembly- https://amzn.to/4my8nBm
EVIL ENERGY ¼ Fuel Hose Line Push Lock NBR Rubber SAE 30R7 5FT 300PSI-
https://amzn.to/4dGRQY0
Rubber Grommet ¾"- https://amzn.to/4khpQMW
Ride Strong Wrench Proud
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