Why install aftermarket mufflers on your motorcycle? For the same reason you double your quarter pounder; it’s better that way.
All joking aside, there are a handful of reasons that folks to remove their stock motorcycle mufflers and replace them with aftermarket parts. From a bike repair after an OEM muffler has been damaged or worn out, to the rider looking to upgrade with premium (and weight-saving) materials for performance, the fact of the matter is that replacing mufflers is a common modification. So let's get into it.
Step 1: Read the instructions!
DISCLAIMER: Legal in California only for racing vehicles which may never be used, or registered or licensed for use upon a highway.
Earning an engineering degree is tough for a reason. It takes a ton of knowledge and skill to make something as complex as a motorcycle perform the way that it does. Parts of your motorcycle exist as they do for a reason (even if we don’t always like that reason), so diving right in without really understanding what you are doing is never a good idea. While this step-by-step aims to give you the broad strokes of the process, it is not a substitute for your factory service manual, or the manual that will come with your new aftermarket muffler. Read them both!
Note: sometimes the installation of a new, non-factory motorcycle muffler will differ from the process of removing the muffler, so pay attention to differences in between the factory and aftermarket manuals.
Step 2: Loosen the connection joint
Your motorcycle muffler will connect to your head pipes in one of a handful of ways. On our BMW F 800, the muffler is secured with a spring-hook system. On your bike, you might be looking at a standard band clamp or gasketed flange. The method differs between bike makers, models, and years, so it is likely that your connection looks somewhat different than is shown here. Regardless, this is the point where you would want to loosen that connection to prepare the mufflers for removal.
Step 3: Loosen the muffler bracket
As with the connection joint, the muffler brackets will vary depending on the motorcycle you are working on. On the F 800, the muffler is held in place with a torx bolt. Again, it’s probable that your setup will look somewhat different, but the basic principle remains the same. Regardless of how your muffler bracket is constructed, it is there to support the weight of the muffler and keep it from causing a ruckus by rattling around.
The main thing you want to keep in mind is to adequately support the muffler can as you are loosening the bracket. As the bracket loosens, the muffler itself can flop around a bit and bang up things that you don’t really want to bang up.
Protip: A tidy shop is a low-stress shop. Be diligent with keeping track of where you put the parts you are removing. Place fasteners some place where you will not lose them!
Step 4: Remove the muffler from the motorcycle
They call them “slip-ons” for a reason. In theory, mufflers should behave in exactly that way. However, as with most things in this world, they do not always behave as advertised. Every now and then when removing mufflers, you may have to exert a little bit of force to get them to dislodge from the home that they have become well acclimated to over the miles.
There is a fine line here, though. At this point your mufflers are still attached to your headers, and your headers are attached directly to your engine. Disturbing these too much can lead to issues with the gaskets, or worse, you could damage a cylinder head (which would suck). Be judicious with the force applied and if you feel like you are yanking a little too hard, stop and verify that all attachments are actually fully removed.
Step 5: Slide the new muffler over the exposed header pipe
At this point, you are basically going to start doing the steps that you have already completed, just in reverse, and perhaps with a minor variation or two. When connecting a new muffler to your motorcycle's head pipe, the number one rule is to proceed carefully! These pieces are designed with precision, so you should not be jamming or slamming things into place. If you find yourself struggling mightily to make something fit, you are likely doing it wrong.
Step 6: Secure the new muffler
Generally speaking, there are two ways to connect your muffler to your motorcycle: by brackets or by band-style clamps. Brackets, like those on our F 800 example, will fasten to both the muffler and the bike. Band-style clamps, on the other hand, act as a holster that will tighten around the muffler to hold it steady. Regardless of what style your bike has, it is important that you fully read the instructions that will come with your new muffler, as it may differ from the stock version you just removed. As can be seen in our example, the Remus exhaust requires the addition of an O-ring that will allow for the proper spacing to be maintained between the can and the bike.
Protip: Finger-tighten everything first to ensure it is in the right place. If something is misaligned and you torque it all the way down, you are more likely to damage the parts. At the very least, it just adds a bit of time and frustration to undo.
Once everything is in alignment, re-attach the springs, flanges, or gasket clamps that are needed to secure the muffler to the head pipe. Overdoing the torque when tightening parts is a common mistake beginners make, so be sure to consult the factory service manual as well as that of the aftermarket slip-on for the exact specs.
Step 7: Wait! Wipe down the muffler
With the new muffler installed and your motorcycle begging to be ridden, this is the part where you undoubtedly want to fire things up and hear the melodic tune of your new slip-on. But don’t! That would be a mistake. Throughout this entire process you have been handling the muffler with, well, your hands. As such (and even though you probably can’t see it), you muffler is now coated with oils from your mitts and needs to be wiped down prior to running. If you run the bike before you have thoroughly wiped the can down, you run the risk of permanently staining your new muffler.
Protip: Proceed with caution around the end caps as they are relatively delicate. Proceed with even more caution if those end caps are made of carbon fiber! Be sure to always use an ultra-clean rag as any specs of dirt can scuff up the carbon fiber outer coat.
Step 8: Check for leaks
Now you can finally flip the switch and dial up that wonderful symphony of motorcycle exhaust sound! Before you go ride, though, you are going to want to be sure and check for leaks around the base of the slip-on and the top of your headers. There should be no exhaust fumes emanating from this part. If there are, something is incorrect.
You can use your hands to check this, but be careful! As anyone who has come too close to a hot motorcycle pipe can attest, the encounter doesn’t tickle, and often results in a solid scar to remind you in the future.
A note about DB killers
We often get asked about DB killers and how they should be handled. For those who don’t know, DB killers are inserts that go into the end of your muffler to subdue the noise levels produced. Some exhausts ship with them, others do not. Some can be removed, others should not. In the end, it all depends on the exhaust. Because the process for removal and insertion varies among different mufflers, it is again imperative that you follow the specific instructions listed with your sip-on’s manual.
The main thing here is to be very careful not to damage your DB killer while removing or handling it. While the idea of a louder motorcycle might sound good in theory, it is very possible that you may not actually be a fan of the muffler tune sans the insert. You may also run into a variety of riding scenarios when a muted exhaust is more desirable (i.e. long motorcycle trips, late nights in quiet neighborhoods, or passengers with sensitive ears). Damaging your DB killer or the DB killer connection on your muffler makes this an irreversible process, so proceed with caution.
Oh yeah… the law
So yeah, there are also some legal things to consider when adding aftermarket modifications (and especially exhausts) to your motorcycle. Be sure to consult the proverbial rulebook for your municipality prior to making any changes. That being said, we need to note that the modification shown in this article is legal in California only for racing vehicles which may never be used, or registered or licensed for use, upon a highway.
And that’s about it. Installing a new motorcycle muffler is a relatively simple task that doesn’t require a ton of technical know-how but packs a substantial bang for your buck when it comes to both the aesthetics and acoustics of a motorcycle. While your bike will undoubtedly differ in some way, shape, or form from our model BMW F 800, the likelihood is high that the general steps listed here will come into play as you work your way through the process on whichever ride you do own.