Yamaha F200C Service Manual page 17

Exhaust passage during idle
To reduce noise when the engine is idling, the exhaust gas passage of the F225 has adopted a lab-
yrinth construction. During idling, the exhaust gas passes through the passage on the side of the
exhaust guide, and enters the upper case through a hole in the upper case gasket. When it fills the
upper case, the exhaust gas enters another passage on the side of the exhaust guide through
another hole in the upper case gasket. Then, it is discharged through the idle port that is provided in
the upper case.
The exhaust manifold and muffler in the upper case are surrounded by the water jackets to reduce
exhaust noise. The water jackets also help prevent corrosion by preventing the exterior of the
exhaust manifold and muffler from coming in direct contact with the exhaust gas.
1 Idle port
2 Oil pan
3 Exhaust manifold
4 Muffler
È Exhaust gas
É Water
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Features and benefits
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