Norton Commando 850 Balanced Pipe Exhaust Seating Cone (065259)

Norton Commando 850 balanced pipe exhaust seating cone (part number 065259) is the correct spherical seating component for the MK3-style balanced pipe exhaust system. Originally introduced on the 1975 Norton Commando 850 MK3 Electric Start model, this improved exhaust design featured a balance pipe (crossover tube) connecting the two cylinders for better exhaust scavenging and mid-range power. This precision-machined cone provides the spherical bearing surface required between the exhaust pipe and the cylinder head — ensuring a gas-tight seal and proper pipe alignment. Worn or damaged seating cones can cause exhaust leaks, rattling pipes, and that characteristic hissing sound of escaping exhaust gases.

The MK3 balanced pipe exhaust system can be fitted to other Norton Commando 850 models as an upgrade from the earlier MK2a twin-pipe design. The spherical seating cones at the head allow the pipes some freedom of movement while maintaining a secure seal under heat cycling and vibration. Over time, these cones can wear, corrode, or get damaged during pipe removal — leading to leaks that not only rob power but also discolor the engine cases with carbon deposits. Replacing worn seating cones restores the factory-spec seal and keeps your exhaust system quiet and leak-free.

Key Features

• Spherical seating cone for Norton Commando 850 balanced pipe exhaust system
• Part number: 065259
• Precision-machined for correct bearing surface and gas-tight seal
• Originally fitted to 1975+ MK3 Electric Start models
• Compatible with MK3-style balanced pipe exhaust retrofits on other 850 models
• Sourced from Norvil – the definitive Norton Commando parts authority

Compatibility

• Norton Commando 850 MK3 Electric Start (1975–1977) – original fitment
• Norton Commando 850 (all models) – when fitted with MK3-style balanced pipe exhaust upgrade

If your balanced pipe exhaust is hissing, leaking, or rattling at the head, inspect this spherical seating cone for wear or damage. Fair Spares New England is your trusted U.S.-based Norvil distributor for classic Norton parts — order with confidence.