Amal Monobloc 389/71 1 1/8″ Carburettor for Norton – Genuine

Amal Monobloc 389/71 carburettor Norton twins — this genuine Amal Monobloc 1 1/8″ (28.5mm) carburettor is the correct replacement unit for Norton parallel twins of the late 1950s and 1960s, including the Norton Atlas, Dominator 88, 99, and 650SS. It is the standard fitment on a wide range of classic British motorcycles.

The Amal Monobloc design integrates a single float chamber body with the mixing chamber for a compact, reliable, and well-proven layout in parallel twin applications. The 389 series Monobloc is ideal for single-carburettor installations on Norton parallel twins.

Standard Jetting Specification

• Part Number: 389/71
• Bore Size: 1 1/8″ (28.5mm)
• Slide: 389/18
• Needle Jet: 106
• Pilot Jet: 30
• Main Jet: 280
• Throttle Valve: 30

Compatibility

This carburettor fits the following Norton models:

• Norton Atlas (1962–1968)
• Norton Dominator 88 (late 1950s–1966)
• Norton Dominator 99 (late 1950s–1966)
• Norton 650SS (1962–1968)
• Norton Wideline Featherbed twins

Jetting may require adjustment to suit individual engine tune, exhaust systems, or altitude. Replacement jets, needles, slides, and rebuild kits for the Amal Monobloc 389 series are available separately. Sourced from Norvil Motorcycle Co. in the UK — the world’s largest supplier of Norton parts — and supplied by Fair Spares New England, your trusted US source for classic Norton and British motorcycle parts.