2004-2009 Honda TRX450R/TRX450ER Service Manual, Page 50Get this manual
TECHNICAL FEATURES
UNICAM SYSTEM
OUTLINE
The Honda Unicam has single overhead camshaft (SOHC) and one-piece camshaft holderThe camshaft acts directly on the intake valves while the exhaust valves are activated by U-shaped roller rocker armThis Unicam design is lighter and more compact than dual overhead camshaft (DOHC) cylinder head designThe Unicam cylinder head incorporates narrow and 22 degree valve angleDECOMPRESSOR ARM LIFTER ARM U-SHAPEDROLLER ROCKER ARM
DECOMPRESSOR WEIGHT
U-SHAPED ROLLER ROCKER ARM
The exhaust roller rocker arm is U-shaped to fit around the centrally located spark plug
AUTO-DECOMPRESSION SYSTEM