Inspect the exhaust layout on your 1981 CB900C Custom before deciding between muffler replacement and joint service. The M.A.C. pair is listed for the factory-style arrangement. Port gaskets are individual pieces, and the stud package has separate stud and nut counts that should be checked before ordering.
Replace one exhaust port gasket on your CB750 or big-bore DOHC CB with this Exhaust Port Gasket, 1 piece, replacing OEM #18291-254-000 / #18291-MM5-860....
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Replace a worn kick stand stopper with this Kick Stand Stopper Rubber "A", a direct replacement for OEM #95011-61000. Exceptionally broad fitment across the...
Replace one cylinder-head-to-exhaust-headpipe gasket on your big-bore Honda with this Cylinder Head to Exhaust Headpipe Gasket, 1 piece, replacing OEM #18291-MM5-860. Exceptionally broad fitment...
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Restore your classic Honda’s exhaust system with this premium Exhaust Stud Set, engineered for durability and a precise fit. This 8-piece kit includes eight...
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Upgrade or restore your classic Honda motorcycle with this Exhaust Pipe Joint Collar — precision‑engineered and made in Japan. This genuine OEM part #18233‑425‑000...
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Drop in a pair of Chrome Slip-On Flare Tip Mufflers from M.A.C. for your Honda CB900C Custom. A direct-fit replacement for factory-style mufflers with...
1981 Honda CB900C Custom · Exhaust Service Choices Buying guide
Identify the exhaust repair before choosing its parts
Muffler fit depends on the retained pipes and supports, while port seals and studs address cylinder-head joints. Compare the actual system, especially if earlier owners changed its headers or mounting points.
Each featured headpipe gasket is one exhaust-port seal. Resealing all four cylinder-head ports needs four individual gaskets; remove the old crush seals from the disturbed joints first. The seals do not replace the joint half-collars, studs or nuts, which need separate inspection.
Check the retained system before choosing slip-ons
The M.A.C. 001-3111 pair is a slip-on replacement for the original-style CB900C exhaust arrangement. Confirm the retained headpipes, balance box, connecting joints and mounting supports before ordering. Its all-steel baffle description does not establish a separate serviceable packing kit or compatibility with an unrelated full-system header.
Buying questions
Will these slip-ons replace a complete aftermarket 4-into-1 system?
They are a paired slip-on set intended for the original-style CB900C arrangement. An aftermarket collector or header can have different outlets and supports. Identify the retained system and confirm those connections before treating the pair as a complete-system replacement.
Does the no-rejetting description cover a modified intake and exhaust?
That description applies to the intended stock-style installation. It does not establish a fuel-setting plan for changed air filters, headers or other engine modifications. Assess the complete installed combination instead of choosing jets from the muffler finish or a general fitment label.
Will an exhaust-port gasket seal a leak at the muffler connection?
Locate the leak before ordering. These individual gaskets seal the headpipe-to-cylinder-head ports. The slip-on connections farther back use their own joint arrangement, so an exhaust-port gasket is not a universal seal for every exhaust leak.
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