For 2017, Honda has completely revamped the big CRF from top to bottom. Among the changes are an all-new Unicam engine with improved power and torque across the rev range. Significant changes to the cylinder head include the use of a finger rocker arm for increased valve lift, and oval-coil cross-section valve springs, the combination of which allows a lower engine height, plus makes the mill more compact and gives it a lower center of gravity. Additionally, the head has a narrower included valve angle (reduced from 21.5 to 19.5 degrees) for a straighter shot into the combustion chamber and improved burn from the mixture. Intake valves are now 2mm larger at 38mm. A new piston combined with a revised combustion chamber raises compression from 12.5 to 13.5:1, new four-hole oil jets for piston lubrication, and a new dual-stage scavenge pump reduce friction enough that oil volume has been reduced from 1,490 to 1,250cc; the lubrication system no longer uses two different oils and reservoirs for engine and gearbox. A new clutch, airbox, and exhaust system round out engine changes, while transmission ratios and final-drive gearing have been altered for the new spread of power.