Fabricating A Custom Built Exhaust
Get the proper angles and curves you want
You can use a stock or aftermarket exhaust as a starting point for a custom motorcycle exhaust, instead of piecing one together totally from scratch.
Starting at the head (in this case a piece of 1.75" tubing that fits over the exhaust spigot on the head), and working your way back, cutting and tacking pieces of tubing to get the proper angles and curves you want.
The spigots on a Triumph head are 1.65" outside diameter, and the inside diameter on the exhaust kit is about 1.64". To be able to clamp the pipes at the head you can just take a grinder with a cut off wheel and cut a .5" notch into the pipe on either side, that allows it to fit over the spigot then compress when you tighten the finned clamp at the head.
This entire set of pipes was completed from start to finish, including the time to figure out a design, in a Saturday morning, about 4 hours not including the final mounts on the rear of the frame for the exhaust. It was completed with a TIG welder, a cut-off saw, 4" grinder, some flap discs, a couple files and a sharpie marker.
Get the proper fitment
Keep checking the fit of your pipes as you go, and as you complete a section you can grind the welds down for a nice smooth finish. Spend the extra time getting proper fitment before you weld to ensure a nice, seamless look.
Fabricating notes
So with the exhaust kit, some basic tools and some patience a unique set of custom pipes was finished on half a Saturday, with exhaust tubing and a bunch of flanges left over. Kyle's fabricating tip: if you plan on welding all weekend check your argon so you don't run out on mid-day Saturday.
A great piece of advice from Derrick (hatchethairy on the JJ): "For all you tig-tackers, try using some hose clamps with holes drilled in it to hold your place while you tack. trust me, it makes a world of difference in time when fitting and welding a set together."
Modifying a Exhaust Kit
You can use a stock or aftermarket exhaust as a starting point for a custom exhaust, instead of piecing one together totally from scratch. What follows is a late-night account of how I did just that to customize the exhaust on my '59 Panhead chopper. I started with a set of Paughco side-by-side header pipes, some bends out of a Biltwell, Inc. Builder Exhaust Kit, and some pieces of ripple pipe.
Defined the look of your pipes
The first step is to figure out exactly how you want your chopper exhaust pipes to look. For me this involved staring at the bike for far too long, then I just decided to start doing it and figured it would turn out how I wanted it in the end. The front pipe (lower) was pretty straightforward, and I was into the fab work and didn't take photos of that, however the process is exactly the same as what follows.
Cut your stock exhaust where you intend to make your first weld. You can carefully grind or sand away the chrome near where you want to weld, or if you are TIG welding it go ahead and weld right through the chrome, it won't affect the weld, though you might want to test it out on a scrap of the cut off chromed pipe first. Take your tubing bends and mark out where you need to cut to get the desired angle. If you have a vertical bandsaw that makes the job easy, however an angle grinder with a cut off disc does a fine job as well. You can start holding pieces up, figuring out lengths and angles as you go.
The final look of your pipes, and the ease of welding and finish-grinding, is affected by the fit of the pieces to be welded. If you get a really nice fit and are TIG welding, you can fusion weld them together with no fill rod. Be sure to make all pieces of pipe square so they butt nice and evenly together. A file does the job, as does a belt sander. I picked up this 48" belt sander Multitool from Van Sant Enterprises and the variety of belts I have for it make for very easy work for squaring the tubing and getting it ready to weld.
Welded the pipe sections together
I TIG welded my pipe sections together one at a time, using mild steel filler and making sure to get good penetration but not using too much filler, which just creates more work to grind it down flush. You can also MIG weld of course, it will give a bit more work with the fatter weld beads.
After welding, I ground down the weld bead flush with the exhaust pipe. You have to take your time doing this as you just want to grind down the weld, not the pipe on either side, if you want a smooth, seamless look for chrome plating. I took the pipe back over to my Multitool belt sander and used a 220 grit belt to carefully bring the weld flush to the pipe surface. You can also file the weld down or use a pneumatic die grinder with some small quick release sanding discs for this job.
Having finished the first section, I held it in place and tack welded it to the chrome header, which was snugged up in place on the exhaust port. This is always easier when you have a second pair of hands! After looking at it from every angle several times I went ahead and finish welded and ground it down. You may find that on some mandrel bends that the pipe may be slightly out of round, in this case you may have to lightly sand the pipe down to feather it out so the multiple pieces join seamlessly.
One of the final steps was to weld up some hidden mounts to keep the exhaust from breaking or wearing out the exhaust spigots. A threaded bung on the rear pipe with a tab welded to the frame gives a nice hidden mount you can't see from the side. On the front pipe I used an 1/8" steel tab and welded it to the back of the pipe, first giving some gentle bends as needed to the tab to keep it from supporting the pipe but not pulling or putting pressure on it, which will lead to a broken mount down the road.
Get exhaust polished and chromed
The finished exhaust. Next step is to get it polished and chromed! Much nicer than an off the shelf set of headers and mufflers, if you make it yourself you don't worry about there being another one out there just like it!
How to Install Exhaust Tips with Ease Steps by Steps
There are several ways you could install exhaust tips, including drilling and tapping or pop riveting them, but here is a nice easy way to install them with just a couple basic tools and hardware.
What to Prepare Before the Exhaust Tips Installation?
Stainless hardware used in this “how to change exhaust tips” guide is included with Lowbrow Customs exhaust tips (available for both 1.5" outside diameter and 1.75" outside diameter exhaust pipes in a variety of styles), and includes a pair of 316 stainless steel 10-32 x 3/8" button head allen bolts and a pair of 316 stainless steel nylock nuts.
The particular pipes in this article were made using the Biltwell Builder Exhaust Pipe Kit, which features 1.75" OD (outside diameter) tubing and assorted HD exhaust flanges. The Shovelhead exhaust flanges included in the kit were used on this set set of custom pipes towards the ends as convenient mounting tabs.
The flange on the exhaust tips shown is .6", a mark is made .25" from the edge of the exhaust pipe. Make sure to drill your mounting hole the bottom or inside edge of the pipe so that when they are mounted the hardware will be hidden.
How to Install Exhausts Tip Steps by Steps?
- Step 1: To make sure your drill bit doesn't wander, center punch your measured mark.
- Step 2: Drill through the Motorcycle exhaust pipe first, then either clamp or firmly hold the exhaust tip in place and drill through it as well. Make sure the tip is thoroughly seated in the pipe before you drill it.
- Step 3: Insert your hardware, and using a 3/8" wrench and an allen, tighten it down, and you are finished.
How to wrap motorcycle exhaust pipe
What Are Motorcycle Exhaust Wrap Pros and Cons?
Here Kyle wraps the pipes on his 2007 Triumph T100. Many people applying exhaust pipe wrap for looks, it can also help hide damaged pipes (such as those on a bike that was in a wreck...Kyle..) or to hide welds or bad chrome / rust.
Another reason why people wrap motorcycle exhaust is to protect their legs from high pipes and excessive heat.
Supplies needed to wrap motorcycle exhaust pipes are:
- A wrap for exhaust pipes (a 2" x 50' roll used here)
- Safety wire and safety wire pliers (or stainless steel zip ties if you want to go that route).
How to Wrap Motorcycle Exhaust Pipes the Easy Way?
Pulled the Motorcycle Exhaust Pipe Off
I pulled the motorcycle exhaust pipe off to make it easier to show but you can do this on the bike as well. Some people use hose clamps to clamp the beginning and end of the exhaust wrap, but I decided to use safety wire instead for a cleaner look.
The safety wire pliers make the job of twisting much easier than doing it by hand. I wrapped tightly around the pipe with an overlap of approximately 1/4", following the manufacturer's directions.
Start Wrapping - Heat Wrap the Exhaust Pipes Dry
I chose to heat wrap my motorcycle exhaust pipes dry, though I know some people wrap the exhaust header with the exhaust wrap wet to get a tighter wrap. If you choose to wrap your pipes wet, simply soak the header wrap in a bucket of water and follow the rest of these directions. Once you start your motorcycle and the pipes heat up, it will dry out the heat wrap right away.
Finish It off: Wiring the End of the Exhaust Wrap
When I came to the end point of where I wanted to wrap, I cut it a bit long and doubled the end over to keep it from unravelling before safety wiring the end of the exhaust wrap.
Run the Pipe to Allow the Exhaust Wrap to Cure
Once you finish wrapping your pipes make sure to run the pipe to allow the exhaust wrap to cure. I would suggest not doing this in your garage or while riding it as it smokes like hell. Once it gets up to temperature it will cure and you will be all set.
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