Honda CRF250F Owner's Manual Installation And Operation page 226

ENGINE
Bore and stroke
Compression ratio
Displacement
Spark plug
Standard
Spark plug gap
Idle speed
Valve clearance (Cold)
71.000 x 63.038 mm (2.80 × 2.48 in)
9.6:1
249.58 cm³ (15.2 cu-in)
LMAR7H-9DS (NGK)
0.8—0.9 mm (0.03—0.04 in)
1,400 ±100 min (rpm)
-1
Intake 0.10 mm (0.004 in)
Exhaust 0.15 mm (0.006 in)
101