Yamaha F6C Service Manual

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7-34

Cylinder head

a Slag or rough surface

3. Adjust the top edge of the valve seat

contact width using a 30° cutter.

b Previous contact width

4. Adjust the bottom edge of the valve seat

contact width using a 60° cutter.

b Previous contact width

5. Adjust the valve seat contact width to

specification using a 45° cutter.

b Previous contact width

c Specified contact width

6. Check the valve seat contact area of the

valve. See “Checking the valve seat” (7-

32).

Example:

• If the valve seat contact area is too wide

and situated in the center of the valve face,

cut the top edge of the valve seat using a

30° cutter, and then cut the bottom edge

using a 60° cutter to center the area and set

its width.

b Previous contact width

• If the valve seat contact area is too narrow

and situated near the top edge of the valve

face, cut the top edge of the valve seat

using a 30° cutter to center the area, and

then set its width using a 45° cutter.

b Previous contact width

45˚

30˚

60˚

45˚

30˚

60˚

30˚

Other manuals for Yamaha F6C

Owner's Manual129 pages

Ower's Manual134 pages

Questions and Answers:

L
Laura HardyAug 19, 2025
Why is my Yamaha Outboard Motor losing power?
- J
  Jason ChavezAug 19, 2025
  If you're experiencing power loss with your Yamaha Outboard Motor, several factors could be responsible. Start by inspecting the propeller for damage and have it repaired or replaced if necessary. Check that the propeller's pitch and diameter are correct for optimal speed. Adjust the trim angle for efficient operation. Ensure that the boat bottom is clean from marine growth, and the gear housing isn't tangled with weeds or other foreign matter. Inspect the spark plugs, replacing them if they are fouled or incorrect. Also, make sure that you are using the specified engine oil. Check the fuel lines and filter for obstructions or clogs, and use clean, fresh fuel.
V
Victoria JohnsonAug 21, 2025
How to fix irregular idling or stalling in a Yamaha F6C Outboard Motor?
- M
  markmorganAug 21, 2025
  If your Yamaha Outboard Motor idles irregularly or stalls, there are several potential causes to investigate. Begin by checking the spark plugs; if they are fouled or the incorrect type, clean or replace them. Inspect the fuel system for any obstructions, such as pinched or kinked fuel lines. Ensure that you're using clean, fresh fuel. Clean or replace the fuel filter if it's clogged. Also, make sure that the air vent screw on the fuel tank is open and the choke knob is in home position. If applicable, ensure the fuel joint connection is correct and the battery lead is securely connected. Check that the motor angle is at normal operating position.