Making a custom motorcycle exhaust is not particularly complex, but it does require a few considerations. First, you must configure the exhaust so it conforms to the motorcycle and allows you to ride without contacting a hot pipe. Another consideration involves positioning the exhaust to avoid damaging the pipe or muffler when leaning into turns. Finally, you must calculate the exhaust pipes' diameter for maximum performance. Oversized or undersized pipes can adversely affect a motorcycle engine. In general, stay within a few millimetres of the stock pipe diameter.
Elevate the motorcycle on a repair stand. Although you can configure and install a custom exhaust with the bike parked on the kickstand or centre stand, a repair stand allows you to perform the work at a convenient level.
Make a template for the exhaust pipe using a 6-foot length of 1/4-inch aluminium rod you can bend by hand. Position one end of the rod at the exhaust manifold on the front of the engine, and make the first bend about 2 inches from the manifold.
Continue to bend and configure the aluminium rod from the engine to the tailpipe, or end of the exhaust pipe. Mark the location of a muffler and the end point of the exhaust pipe with a felt marker. You do not need to mark for a muffler when you plan to use baffles.
Measure and cut a length of exhaust pipe tubing by transferring the measurements from the aluminium bar. Cut the pipe using a hacksaw, and file any burrs on the cut using a flat file. Flare the end of the pipe where it attaches at the exhaust manifold using a flaring tool.
Mark the locations of the bends in the length of exhaust pipe with your felt marker.
Bend the pipe in a tubing bender using the aluminium bar as a guide for the degree of the bends.
When a flaring tool and tubing bender are not available, take the configured aluminium bar and raw piping to a muffler shop and have the pipe bent and flared.
Measure the length of the muffler, and transfer the measurement onto the exhaust pipe. Cut the pipe at each point where you plan to install the muffler, and remove the cut section. File the burrs at the end of each section of exhaust pipe with the flat file. Omit this step if you plan to use baffles.
Put the manifold flange used with the stock pipe onto the front section of the exhaust pipe; slide it against the flared end of the pipe. Proceed to the next step to install a muffler.
Install exhaust pipe inserts at the ends of the pipe where the muffler connects. Depending on the style of the inserts, install them by either using a rubber mallet to tap them into the ends of the pipe or tightening the provided clamps with a screwdriver. Connect the muffler between the front and back sections of the exhaust pipe.
Install a new exhaust manifold gasket, and attach the pipes at the manifold. Typically, this attachment involves sliding the manifold flange onto threaded studs and securing it with hex nuts. Tighten the nuts with a box wrench or a socket and ratchet.
Attach the exhaust pipe to the motorcycle frame using exhaust pipe brackets. Include a bracket at each end of the muffler. If you plan to use baffles, drill the exhaust pipe at the preferred location and install the baffles using the provided clips or nuts.
Have the pipe chromed or wrapped before installing the exhaust. Test-ride the motorcycle, then tighten brackets or manifold nuts as needed.