Creating a truly unique motorcycle will hinge heavily upon the sum of its parts. A set of custom exhaust pipes is absolutely critical to the appearance of the machine. While an assortment of aftermarket exhaust systems are available for purchase, fabricating a complete system from scratch can be extremely rewarding and lend that final touch to your custom motorcycle. Be warned, welding and metalworking skills are absolutely required to complete this project.
Sketch your concept on paper, including mounting details and muffler arrangements. Take measurements with a flexible tape measure from the motor's exhaust ports to the exhaust pipe's final mounting point. Be sure to measure the distance from each exhaust port to the pipe's final mounting point, as the lengths will differ between each port. Write these measurements down to help you determine the amount of tubing you will need.
Select your exhaust tubing. Stainless steel exhaust tubing is ideal due to its resistance to heat and corrosion and is often available in pre-bent sections, eliminating the need for an expensive tubing bender. Using the measurements taken in Step 1, obtain enough tubing to complete the exhaust system with a minimum of 2 feet of excess tubing.
Cut the flanged end of the motorcycle's stock header tubes with a metal cut-off wheel attached to an angle grinder. Begin the cut a minimum of 2 inches below the curve of each tube to allow extra room for the new tubing. Insert the cut header tubes into the exhaust port and rotate them into the desired position.
Cut your exhaust tubing into smaller sections as desired to match your concept. Place the first section against the header tube and tack weld it into place. Continue placing the sections of tubing and tack welding them into place until you have completed the exhaust's basic design.
Test-fit the mufflers, if any, onto the exhaust system. Make adjustments as necessary, grinding the tack weld off the misaligned section of tubing with an angle grinder. Reposition the section and tack weld it into place.
Remove the mufflers and the entire tack-welded exhaust from the motorcycle. Weld the joints between each exhaust section, completely sealing the joints. Smooth the weld beads using an angle grinder until you have attained your desired finish.
Install the completed exhaust and mufflers onto the motorcycle. Alternatively, the exhaust may be finished with chrome or powder-coating from a chrome shop.
Always double-check your measurements before cutting your tubing. Your motorcycle's air-to-fuel ratio will be changed by the new exhaust pipes, affecting the machine's performance. Adjust the carburettor or fuel-injection system to compensate for the changes to restore performance.
Always wear proper safety equipment while cutting or working with metal.