| Specification | Data |
|---|---|
| Production Years | 2004-2009 |
| Engine Oil | SAE 10W-30 JASO T 903 MA (0.66 L) |
| Transmission Oil | SAE 10W-30 JASO T 903 MA (0.60 L) |
| Front Tire | 80/100-21 51M (1.0 bar / 15 psi) |
| Rear Tire | 100/90-19 57M (1.0 bar / 15 psi) |
| Spark Plug | NGK IMR8C-9H |
The Honda CRF 250 R (ME10 series) holds a significant place in motocross history as Honda’s first dedicated 250cc four-stroke racing machine. Its primary engineering highlight is the Unicam® valve train. Unlike traditional DOHC designs that use two camshafts, the Unicam system uses a single overhead cam to directly actuate the intake valves while using forked low-friction roller rocker arms for the exhaust valves. This configuration significantly reduced the engine’s overall height and weight, allowing for a lower center of gravity and better centralization of mass.
Technical Engineering Analysis
The ME10A/B generation was designed to bridge the gap between the agility of 125cc two-strokes and the power of 450cc four-strokes. The liquid-cooled, 249cc engine features a high-revving architecture that necessitates precise maintenance. One of the unique aspects of this model is the dual-sump lubrication system. By separating the engine oil from the transmission oil, Honda ensured that the clutch debris would not contaminate the engine oil, allowing the high-performance top-end to run on cleaner lubricant for longer periods.
Maintenance Essentials
To maintain peak performance and prevent premature wear of the titanium valves, strict adherence to the service schedule is mandatory for the CRF 250 R.
- Oil Management: Use only JASO T 903 MA rated oils. The engine side requires 0.66 Liters, while the transmission requires 0.60 Liters. Frequent changes (every 15 hours of operation) are recommended for racing conditions.
- Ignition: The NGK IMR8C-9H is a laser-iridium plug specifically indexed for this high-compression combustion chamber. Do not substitute with standard copper plugs.
- Tire Pressures: For optimal traction on intermediate terrain, maintain 1.0 bar (15 psi) in both the 21-inch front and 19-inch rear tires.
Expert Verdict
From an engineering standpoint, the 2004-2009 CRF 250 R is a masterpiece of compact packaging. However, the ME10 generation is known for being sensitive to valve clearance issues. Owners must perform regular shim-under-bucket adjustments to ensure the titanium intake valves do not ‘stretch’ and cause hard-starting issues. When properly maintained, it remains one of the most balanced and flickable motocross bikes of its era.