2008 Yamaha YZ250F
General Specifications
| Model | Yamaha YZ250F |
| Year | 2008 |
| Category | Motocross |
| Engine Type | Liquid-cooled, 4-stroke, DOHC, 5-valve single-cylinder |
| Weight | 92.7 kg dry |
Engine
| Displacement | 249 cc |
| Bore x Stroke | 77.0 x 53.6 mm |
| Compression Ratio | 13.5:1 |
| Fuel System | Keihin FCR-MX37 flat-slide carburettor | Replacement Options |
| Ignition | CDI magneto |
| Spark Plug | NGK CR8E resistance type |
| Spark Plug Gap | 0.7-0.8 mm (0.028-0.031 in) |
| Cooling System | Liquid cooled |
| Starting System | Kick starter with automatic decompression |
Transmission
| Transmission | 5-speed constant-mesh |
| Clutch | Wet multi-plate |
| Final Drive | Chain, 13-tooth front / 49-tooth rear sprocket, 3.769:1 |
Dimensions
| Overall Length | 2,162 mm |
| Overall Width | 825 mm |
| Overall Height | 1,300 mm |
| Wheelbase | 1,469 mm |
| Ground Clearance | 370 mm |
| Seat Height | 985 mm |
| Fuel Capacity | 7.0 L |
Chassis
Suspension
| Front Suspension | 48 mm KYB inverted Speed Sensitive System cartridge fork, adjustable compression and rebound damping | Fork Oil Levels |
| Front Suspension Travel | 300 mm (11.8 in) |
| Rear Suspension | Link-type Monocross with KYB gas/oil shock, titanium spring and adjustable preload, high-/low-speed compression and rebound damping |
| Rear Suspension Travel | 310 mm (12.2 in) for Australian specification |
| Fork Oil | Yamaha Suspension Oil S1; approximately 195 cc damper assembly fill and 340 cc standard outer chamber oil quantity per fork |
Brakes & Wheels
| Front Brake | Hydraulic single disc, 250 mm |
| Rear Brake | Hydraulic single disc, 245 mm |
| Front Wheel Size | 21 x 1.60 in aluminium spoked wheel |
| Rear Wheel Size | 19 x 1.85 in aluminium spoked wheel |
Service Data
| Fuel Type | Premium unleaded petrol, minimum 95 RON |
| Premix Information | Not applicable - 4-stroke engine |
| Gearbox Oil | Engine and transmission share the same dry-sump engine oil supply; 1.05 L periodic oil change, 1.15 L with oil filter replacement, 1.30 L total capacity. API SG or higher, JASO MA motorcycle oil. |
| Air Filter | Wet-type foam element |
| Service Notes | Dry-sump lubrication. Maintain frequent oil and filter changes, regularly inspect valve clearance, keep the foam air filter clean and correctly oiled, and maintain correct FCR carburettor jetting and accelerator-pump operation. Standard tyre pressure is 100 kPa (15 psi) front and rear. |
2008 Yamaha YZ250F: More Compression and Sharper Suspension
The 2008 Yamaha YZ250F was an evolutionary development of the aluminium-framed generation rather than an all-new model. Yamaha retained the established five-valve engine and chassis layout but made targeted changes to increase performance and improve the suspension package.
The biggest engine change was a new lightweight high-compression piston that raised the compression ratio from 12.5:1 to 13.5:1. Yamaha also revised the ignition mapping and Keihin FCR-MX37 carburettor jetting, including a new needle profile, while clutch oil flow was increased to improve durability. Owners maintaining the original carburettor can compare replacement and tuning options through the MXOwners carburettor reference.
Suspension received equally useful attention. The 48 mm KYB Speed Sensitive System fork used stiffer springs and revised damping, while the rear Monocross system gained a revised rising-rate linkage, firmer titanium spring and altered damping. These changes were aimed at improving support for faster riders without sacrificing compliance. Fork servicing information can be checked through the MXOwners fork oil reference.
The aluminium semi-double-cradle frame, five-speed gearbox and dry-sump lubrication system remained familiar. Engine and transmission share the same oil supply, with 1.05 litres required for a routine change and 1.15 litres when replacing the filter.
For current owners, the 2008 YZ250F represents a well-developed version of Yamaha's carburetted aluminium-frame generation. Model-specific engine and suspension parts should be checked carefully through the MXOwners Parts Finder, while the original 80/100-21 front and 100/90-19 rear tyre sizes can be compared using the MXOwners Tyre Size Guide.
