R100 (Familia Rotary)

1968-1973 / Coupe / Japan

All R100 (Familia Rotary) problems All workshop issues

Common Fuel System

Carburettor Deterioration

Symptoms

Poor idle quality, flat spots during acceleration, hesitation off idle, fuel leaks from the carburettor body, flooding, or lean running.

Cause

The R100's carburettor (typically a Hitachi or Nikki unit) has internal gaskets, needle valves, diaphragms, and float mechanisms that degrade over 50 years. Ethanol-blended fuels accelerate the deterioration of rubber components.

Fix

Complete carburettor rebuild.

Kits are still available through Japanese parts suppliers and some Australian rotary specialists.

Ultrasonic cleaning of the body is recommended.

Replacement carburettors from donor cars may be available.

Some owners convert to a Weber DCOE sidedraft setup for improved performance, this works well but sacrifices originality.

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Other known issues

Common Fuel System

Fuel Tank Corrosion

Restricted fuel flow, debris in the fuel system, fuel leaks from the tank.

Minor Engine, 10A Twin-Rotor (982cc)

Apex Seal Wear

Gradual loss of compression, resulting in reduced power, increasingly difficult cold starts, blue-white exhaust smoke (burning oil), and eventually rough idle, misfiring, and inability to maintain running at low RPM.

Minor Engine, 10A Twin-Rotor (982cc)

Oil Metering Pump Failure

The apex seals lose their lubrication source. Wear accelerates dramatically, and the engine may seize if run for extended periods without lubrication.

Critical Engine, 10A Twin-Rotor (982cc)

Cooling System Inadequacy

The engine overheats, particularly in traffic, on hot days, or under sustained load. The temperature gauge climbs, coolant may boil over, and the engine suffers heat distortion or blown coolant seals.

Common Engine, 10A Twin-Rotor (982cc)

Exhaust Port Gasket Leaks

Exhaust gas leaks at the junction between the exhaust manifold and the engine's exhaust ports. Audible ticking sound that increases with RPM. May cause exhaust fumes in the cabin.

Minor Body and Rust

Floor Pan Corrosion

The floor pans perforate, weakening the car's structure and allowing moisture and exhaust fumes into the cabin.

View all 13 R100 (Familia Rotary) problems