Harley Davidson exhaust systems dampen engine exhaust noise and provide a precisely metered amount of back-pressure to the system. The back-pressure created at the muffler is an important part of the air/fuel circuit and has a strong impact on maintaining the air/fuel charges entering the cylinders. Harley motorcycles employ a two-part exhaust system consisting of an exhaust pipe leading from each cylinder head and terminating close to the rear of the vehicle. Slip-on mufflers are clamped onto each pipe and then mounted to a bracket at the rear of the bike. The pipes also incorporate a crossover tube to assist the backpressure and aid in exhaust gas scavenging in the heads.
1. Loosen the clamp where the exhaust pipe enters the muffler, with a socket. Slide the clamp forward and allow it to rest on the exhaust pipes.
2. Loosen with a socket and remove nuts on the muffler T-bolts where they enter the rubber mounted exhaust bracket. Lower the muffler away from the frame and wiggle it gently to loosen the slotted muffler sleeve at the pipe. Support the exhaust pipe with one hand and pull the muffler off the pipe with the other to avoid stressing the exhaust pipe gasket. Remove the T-bolts from the muffler and insert them in the muffler mount slot.
3. Push the new muffler onto the exhaust pipe. Support the pipe with one hand and the muffler with the other. The muffler may have to be wiggled on in order to spread the slotted clamp sleeve enough to fit onto the pipe. Slip the pipe in about two inches.
4. Rotate the muffler until the T-bolts are lined up with the exhaust support bracket. Insert the T-bolts in the bracket and tighten the nuts hand-tight.
5. Slide the exhaust clamps back onto the slotted clamp sleeve and torque them to factory specifications with a torque wrench and socket. Torque the T-bolt nuts to factory specifications with a torque wrench and socket.
6. Use brake cleaner and a clean shop rag to remove all fingerprints and oils from the muffler and the exhaust pipes. Any oily spots will permanently discolor the chrome components once the pipes heat up to operating temperature.