2001 Edition Yamaha F225A and LF225A Outboards Service Manual, Page 14Get this manual
GEN INFO
General information
Valve train system
The valve train consists of total of four camshafts, with two in each bankThe camshafts are driven with the combination of belt and chainsThe crankshaft turns the belt to drive the exhaust camshafts in both banksChains connect the exhaust camshafts to the intake camshafts in the cylinder heads to drive the intake camshaftsIn addition, the timing belt offers quieter operation, and the cam chains help to achieve compact configuration through the use of individual driven sprocketsTiming belt The timing belt, which is driven by the drive sprocket that is attached to the crankshaft, rotates the driven sprockets that are attached to the exhaust camshafts of both banksThe drive sprocket for the timing belt is secured to the crankshaft by four bolts, and it can be removed easily for servicingIn addition, the material of the driven sprockets has been changed from the previous metal to plastic for weight reduction