This article examines the differences between dual and single motorcycle exhausts.
Motorcycle exhausts come in a variety of configurations. From single-cylinder engines with just one exhaust to 6-cylinder engines with a separate exhaust pipe for each cylinder.
But let’s focus on single and dual motorcycle exhausts. What are the advantages and drawbacks of each? Can you put dual exhausts on a single-cylinder motorcycle and vice versa? More importantly, SHOULD you?
If you are scratching your head trying to answer these questions, we’ll help you. We’ve been riding and working on motorcycles for the past ten years, so we know a thing or two about them!
Keep reading to find the key differences between single and dual motorcycle exhausts.
At a Glance
When it comes to motorcycle exhaust configurations, the world is your oyster. You can get a single exhaust for a single-cylinder bike. Or you can outfit the same motorcycle with a ‘1-into-2’ style exhaust which splits the pipe into two at the end.
Similarly, you can install dual exhausts on a twin-cylinder motorcycle, like a Harley Davidson. Or you can get a ‘2-into-1’ style pipe for the same bike and merge both header pipes into one.
All of these configurations have their benefits and drawbacks. And while there are plenty of performance sound features to consider, which one you choose depends greatly on personal preference.
Which exhaust configuration is best?
If only it were that easy! The fact is that there are hundreds of different combinations when it comes to the number of exhausts and the number of engine cylinders.
For convenience, we will only be talking about single and twin-cylinder motorcycles. We will also be comparing exhaust setups for these bikes separately to avoid confusion. This will also ensure that the matchup is somewhat fair.
And while there are also motorcycle engines with 3, 4, and 6 cylinders, we will save those for a different article.
Single vs. Dual Exhausts: Single Cylinder
In a single-cylinder motorcycle, you won’t notice the most significant difference between single and dual exhausts when it comes to sound. Sure, the freer-flowing system might enable a slightly different sound, but having two mufflers might make the motorcycle quieter than when it had a single exhaust.
If you thought slapping on another exhaust pipe on your bike would give you an instant power boost, you’re not wrong. Dual exhausts allow for higher gas flow, thus making combustion more efficient. However, there are some caveats.
Firstly, you only get higher power from dual exhausts if the engine displacement is higher. In this case, a single exhaust setup would be the bottleneck that prevents excess exhaust gasses from being ejected quickly.
By increasing the area for exhaust gasses to be ejected, you could boost power slightly. However, with a single exhaust setup, most single-cylinder bikes are already getting rid of exhaust gasses as efficiently as possible. Add to that the fact that most single cylinders top out at around 650cc, and the case for single exhausts becomes stronger.
Which exhaust configuration is better for single-cylinder motorcycles?
Single-cylinder motorcycles perform better with a single exhaust setup. A dual exhaust setup might look cool but doesn’t add many performance or sound benefits.
Single vs. Dual Exhausts: Twin Cylinder
When it comes to twin-cylinder motorcycles, you get slightly better acoustics with a dual exhaust setup. This can vary depending on the particular bike, its displacement, and other features. But for our money, the dual exhaust setup just sounds more ‘rumbly’ and full compared to single exhausts.
Dual exhausts are also louder than single exhausts on twin-cylinder motorcycles.
Again, dual exhausts favor larger displacement engines to improve performance. So you pretty much have to have a larger engine if you want to extract more power via dual exhausts.
This is because the larger displacement engine produces more exhaust gasses. The dual setup provides a larger area for those gasses to flow freely. This results in the whole process becoming more efficient.
Twin-cylinder engines, such as those found on Harleys, tend to be larger in displacement. Opt for a dual exhaust setup to get better performance from your twin-cylinder engine.
That said, single exhausts for twin-cylinder engines, i.e., ‘2-into-1’ setups enable a phenomenon called ‘scavenging.’ In simple terms, scavenging is when a pulse of exhaust gas from Cylinder 1 causes more oxygen to be sucked into Cylinder 2, and vice versa.
Which exhaust configuration is better for twin-cylinder motorcycles?
Keeping all of the factors mentioned above in mind, we think you are better off getting a dual exhaust setup for your twin cylinder motorcycle. They will make the sound quality better than a single exhaust.
Furthermore, if you want the benefit of scavenging while still running a dual exhaust setup, there are ‘2-into-1-into-2’ exhausts that give you the best of all worlds.
Next, irrespective of how many engine cylinders there are some factors apply to this comparison
This is pretty easily understood. Dual exhausts are larger, bulkier, and use more metal than single exhausts. If you want to cut weight, opt for a single exhaust setup.
More hardware equals higher cost. If you’re balling on a budget, single exhausts tend to be a little bit more affordable than their dual counterparts.
Dual vs Single Motorcycle Exhausts: The Winner
So with all of those factors in mind, it is clear that no one exhaust configuration is perfect for every situation. Generally, single exhausts work well with single-cylinder bikes and dual exhausts with twin-cylinder bikes.