The Honda EN1 is a 547 cc, inline‑two naturally aspirated petrol engine produced between 1985 and 1992. It features a single overhead camshaft (SOHC) 6‑valve design with Honda's PGM‑Carb fuel system. This compact configuration prioritized lightweight packaging and fuel efficiency, making it ideal for kei-class city mobility.
Fitted primarily to the first-generation (JA4/5) Honda Today and the Honda Acty van, the EN1 was engineered for economical urban transport and light commercial use. Emissions compliance for its era was managed through precise carburetion and ignition control, meeting applicable Japanese Showa 60 kei car regulations.
One documented service consideration is the potential for carburetor float bowl sediment buildup, leading to erratic idle or fuel starvation, as noted in Honda Service Bulletin 87‑011. This is typically caused by infrequent fuel filter changes or use of degraded fuel. The engine was succeeded by the more powerful E07A in 1993.
Production years 1985–1992 meet applicable Japanese Showa 60 emissions standards for kei-class vehicles (MLIT Type Approval JH3‑TODAY‑85).
The Honda EN1 is a 547 cc inline‑two naturally aspirated petrol engine engineered for kei-class applications (1985-1992). It combines SOHC 6-valve architecture with a carbureted fuel system to deliver maximum fuel efficiency and low-cost ownership. Designed to meet contemporary Japanese kei car regulations, it prioritizes urban practicality over performance.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 547 cc | |
| Fuel type | Petrol (Gasoline) | |
| Configuration | Inline‑2, SOHC, 6‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 61.0 mm × 62.0 mm | |
| Power output | 33 kW (45 PS) @ 7,500 rpm | |
| Torque | 50 Nm @ 5,500 rpm | |
| Fuel system | Honda PGM‑Carb (Programmed Carburetion) | |
| Emissions standard | Japanese Showa 60 (Kei Car) | |
| Compression ratio | 9.2:1 | |
| Cooling system | Water‑cooled | |
| Turbocharger | None | |
| Timing system | Chain‑driven SOHC | |
| Oil type | API SF 10W‑40 | |
| Dry weight | 68 kg |
The SOHC 6-valve design provides adequate low-RPM torque for city driving but requires precise valve clearance adjustments every 20,000 km. Using the specified API SF oil is critical for protecting the engine's older metallurgy. The PGM-Carb system is sensitive to fuel quality; sediment buildup in the float bowl can cause running issues. The chain-driven timing system is robust but should be inspected for wear at high mileage. The non-interference design offers peace of mind if the timing chain fails.
Oil Specs: Requires API SF specification (Honda Owner's Manual). Modern API SN/SP 10W-40 is an acceptable equivalent.
Emissions: Japanese Showa 60 kei car certification applies to all 1985-1992 models (MLIT Type Approval JH3-TODAY-85).
Power Ratings: Measured under JIS D 1001 standards. Output is consistent across all model variants (Honda Workshop Manual).
Honda Technical Information System (TIS): Workshop Manual (1985), SIB 87-011
Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) Type Approval Database
Honda EPC (Electronic Parts Catalogue) Doc. H-EN1-85
JIS D 1001 Engine Power Measurement Standards
The Honda EN1 was used across Honda's JA platforms with transverse mounting and was not licensed to other manufacturers. This engine received minor platform-specific adaptations-different intake manifolds and engine mounts between the Today and Acty-but no major facelift revisions occurred during its production run, ensuring broad parts interchangeability. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, just below the cylinder head and behind the alternator (Honda Workshop Manual). The 8th VIN digit for EN1-equipped JA Today is typically 'J'. Visually, it features a black or silver valve cover with "SOHC" embossed on top. Critical differentiation from the E07A: The EN1 is an inline-two engine, while the E07A is a three-cylinder. The carburetor has a distinct PGM-Carb label on its side.
The EN1's primary long-term concern is carburetor float bowl sediment, with elevated incidence in vehicles using degraded fuel or with neglected maintenance. Honda service data indicates this is a common fuel system issue, while owner reports frequently cite distributor cap and rotor wear. Neglected valve adjustments can lead to poor performance, making preventative maintenance critical.
Analysis derived from Honda technical bulletins (1985-1992) and aggregated owner workshop data (1987-2023). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA EN1.
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