Motorcycle exhaust baffles serve two purposes: reduce the noise from wide-open exhaust pipes and create back-pressure in the exhaust system. Limiting noise emission is not only considerate, but is required by law in many localities. Those with knowledge of motorcycle engines also understand a certain amount of back-pressure is needed to avoid damaging a stock engine. Baffles are not complex pieces of equipment. Typical baffles consist of steel tubing with a series of offsets that combine to reduce noise and create that necessary back-pressure. You can make motorcycle exhaust baffles in your workshop with standard tools.
Measure the inside diameter of the motorcycle tailpipe. Obtain a short length of steel tubing that has an outside diameter 1.5 mm (1/16 inch) less than the inside diameter of the tailpipe. The overall length of the steel tubing depends on the number of baffles you intend to make. Typical baffles are 20 cm (8 inches) long.
Secure the steel tubing in a bench vice and cut an 8 inch baffle using a hacksaw. Mark the baffle for three offsets using a felt-tip marker. The first offset is 7.5 cm (3 inches) from one end. The second is 3.7 cm (1 1/2 inch) from the first mark. The third offset is 7.5 cm (3 inches) from the first mark.
Secure one end of the baffle vertically in the bench vice with the offset marks above the vice. Make horizontal crosscuts halfway through the baffle at each of your marks with a hacksaw. Reposition the baffle in the vice if necessary as you go. Remove the baffle from the vice.
Place the baffle on the workbench with the hacksaw cuts facing up. Secure the baffle in place using one or more c-clamps.
Position the tip of a cold chisel at the first hacksaw cut. Strike the cold chisel with a mallet to force the outer edge of the cut into the centre of the baffle. Repeat this at the remaining hacksaw cuts to create the baffle offsets.
Secure the baffle in the vice with the 7.5 cm (3 inch) end of the baffle extending from one end of the vice. Chuck a 5 mm (3/16 inch) drill bit in an electric drill. Drill a hole 2.5 cm (1 inch) from the end of the baffle and through both walls of the baffle. The hole is used for a stainless steel bolt that holds the baffle in the tailpipe.
Mark and drill a 5 mm (3/16 inch) hole through the tailpipe that aligns with the bolt holes in the baffle. Once installed, the outside end of the baffle should be flush with the end of the tailpipe. Secure the baffle in the tailpipe with a 6 mm (1/4 inch) diameter stainless steel bolt, lock washer and nut. The length of the bolt depends on the outside diameter of the tailpipe.
Look at other baffle configurations on motorcycle accessory websites. Consider soldering or welding methods to make other types of baffles.
Wear safety glasses and work gloves when making baffles.