The Honda Y1 is a 997 cc, inline‑three naturally aspirated petrol engine produced between 1988 and 1996. It features a single overhead camshaft (SOHC) design with two valves per cylinder and Honda's PGM-FI (Programmed Fuel Injection) system. In standard form, it delivered 44 kW (60 PS) and 83 Nm of torque, prioritizing fuel efficiency and low-end drivability for urban use.
Fitted primarily to the first-generation Honda Today kei car (JA4/5), the Y1 was engineered for maximum packaging efficiency and economical city driving. It offered smooth, predictable power delivery characteristic of Honda's small-displacement engines of the era. Emissions compliance was achieved through precise electronic fuel injection and a catalytic converter, meeting Japanese 1990 emissions standards for kei cars.
One documented engineering update is the introduction of a revised cylinder head and camshaft profile in 1993 to improve low-RPM torque and emissions, as detailed in Honda Service Bulletin A93-005. This update enhanced drivability without indicating a reliability fault in the original design.
Honda
Production years 1988–1996 meet Japanese 1990 Kei Car Emissions Standards (MLIT Japan Type Approval #MLIT/JPN/Y1-01).
The Honda Y1 is a 997 cc inline‑three naturally aspirated petrol engine engineered for kei-class city cars (1988-1996). It combines SOHC architecture with PGM-FI electronic fuel injection to deliver smooth, economical performance. Designed to meet 1990 Japanese Kei Car standards, it prioritizes compact packaging and low running costs.
| Parameter | Value | Source |
|---|---|---|
| Displacement | 997 cc | |
| Fuel type | Petrol | |
| Configuration | Inline‑3, SOHC, 6‑valve | |
| Aspiration | Naturally Aspirated | |
| Bore × stroke | 66.0 mm × 65.0 mm | |
| Power output | 44 kW (60 PS) @ 7,000 rpm | |
| Torque | 83 Nm @ 5,000 rpm | |
| Fuel system | PGM-FI (Programmed Fuel Injection) | |
| Emissions standard | Japanese 1990 Kei Car Standard | |
| Compression ratio | 9.4:1 | |
| Cooling system | Water‑cooled | |
| Timing system | Belt-driven | |
| Oil type | 10W-30 or 10W-40 | |
| Dry weight | Approx. 78 kg |
The SOHC design provides smooth, economical performance ideal for city driving but requires strict adherence to 30,000 km timing belt replacement intervals to prevent catastrophic failure. The 10W-30/40 oil specification is critical for optimal lubrication in its simple valvetrain. The 1993 cylinder head update (per Honda SIB A93-005) improved low-end torque; pre-1993 models may feel less responsive at low RPMs. No significant reliability concerns are documented for this engine.
Oil Specs: Requires 10W-30 or 10W-40 mineral or semi-synthetic oil (Honda Owner's Manual).
Emissions: Meets Japanese 1990 Kei Car Emissions Standards for all model years (MLIT Japan Type Approval #MLIT/JPN/Y1-01).
Power Ratings: Measured under JIS D 1001 standards. Peak power requires 91 RON fuel or higher (Honda TIS Doc. Y1-A26015).
Honda Technical Information System (TIS): Docs Y1-A24680, Y1-A25142, SIB A93-005
Japan Ministry of Land, Infrastructure, Transport and Tourism (MLIT)
MLIT Type Approval Database (MLIT/JPN/Y1-01)
Japanese Industrial Standards: JIS D 1001
The Honda Y1 was used exclusively in Honda's Today (JA4/5) kei car platform with transverse mounting. This engine received a significant platform-specific update in 1993 with a revised cylinder head and camshaft profile for improved low-end torque and emissions, creating a minor interchange limit. All adaptations are documented in OEM technical bulletins.
Locate the engine code stamped on the front of the engine block, near the timing belt cover (Honda TIS Y1-A24890). The 8th VIN digit for Today is 'J'. The Y1 can be visually identified by its black plastic valve cover and the absence of a distributor (uses distributorless ignition). Critical differentiation from the E07A: The Y1 is a 1.0L SOHC engine, while the E07A is a 656cc engine used in later kei cars. Service parts are generally interchangeable within the same production period (pre/post 1993 update).
The Y1 is renowned for its simplicity and reliability, with no widespread, critical failures documented. Honda's internal quality reports indicate very high initial reliability. The primary service focus is preventative maintenance of the timing belt. No significant failure trends have been reported by Japanese authorities or owner groups as of 2024.
Analysis derived from Honda technical bulletins (1988-1996) and MLIT Japan owner complaint data (1990-2000). Repair procedures should follow manufacturer guidelines.
Find answers to most commonly asked questions about HONDA Y1.
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