| Specification | Data |
|---|---|
| Production Years | 2004–2009 |
| Engine Oil | SAE 10W-30/10W-40 (0.69 L Engine / 0.60 L Transmission) |
| Spark Plug | NGK R0452A-9 |
| Tire Size (Front/Rear) | 80/100-21 / 100/90-19 |
| Tire Pressure | 1.0 bar (15 psi) Front & Rear |
| Starting System | Kick-start (No Battery) |
The Honda CRF 250 R (ME10A/H), introduced in 2004, marked a revolutionary shift in the quarter-liter motocross class. It was the first production 250cc four-stroke to utilize Honda’s proprietary Unicam cylinder head design. By using a single overhead cam to actuate the intake valves directly and the exhaust valves via a forked roller rocker arm, Honda achieved a compact engine profile that rivaled the weight and center of gravity of contemporary two-strokes.
Engineering Overview: The ME10A/H Platform
One of the most distinctive technical features of the ME10A/H series is the dual-sump lubrication system. Unlike most four-strokes of the era, Honda separated the engine oil from the transmission oil. This prevents clutch debris and transmission metal shavings from contaminating the high-performance top end, ensuring that the Unicam assembly receives the cleanest possible lubrication. This design necessitates two separate oil changes during routine maintenance.
Maintenance Protocols
Lubrication Management
For optimal performance, MotoSpecsLab recommends high-quality synthetic oils meeting JASO MA standards. It is critical to use a non-moly oil in the transmission side to prevent clutch slippage. The engine requires 0.69 liters, while the transmission requires 0.60 liters. We recommend changing both every 15 hours of track use, or more frequently under racing conditions.
Ignition & Combustion
The ME10A/H utilizes the specialized NGK R0452A-9 spark plug. This plug is designed to withstand the high vibration and extreme heat cycles of a 13,000+ RPM engine. Given the kick-start nature of this bike, maintaining a clean plug and a properly adjusted pilot screw is essential for easy starting.
Chassis & Tires
The chassis is optimized for a 80/100-21 front and 100/90-19 rear tire configuration. To maintain the intended carcass profile and contact patch, a standard pressure of 1.0 bar (15 psi) is recommended for intermediate terrain. Lowering pressure to 12-13 psi may be beneficial in soft sand, but increases the risk of pinch flats on the ME10A/H’s lightweight rims.
Expert Verdict
The 2004–2009 CRF 250 R remains a benchmark for handling and ergonomic design. While it requires more diligent maintenance than its modern fuel-injected successors—particularly regarding valve clearance inspections and carburetor jetting—it offers a pure, mechanical racing experience that defined an era of motocross. For the technician, the ME10A/H is a masterclass in packaging and weight distribution.