Parts name need to know, please help

[Jason and Lund]

This picture is taken from my Yamaha 4 stroke outboard. I'd like to know the name of parts with question marks in this picture. My friend adjust the coper part to increase idle speed . I think I may adjust the lower screw with spring which marked question mark. which way is the right way to increase idle speed. Thanks

[boscoe99]

Is the model of the motor not known?

[99yam40]

I am not sure the OP even knows what motor he has, much less us

[Jason and Lund]

is the model of the motor not known?

1997 f50tlrv.

[Jason and Lund]

I am newbie for the this outboard motor, if I know the name I can google it to know what the function of this part. Thanks

[fairdeal]

Here it is:
good luck, since it seems to be just one of two diaphragms on that engine,
I have no idea what it does or why...

[/url]

[boscoe99]

Friends don't let friends mess with their motors.

What is your service manual indicating as the means to adjust the idle RPM?

The copper coloured part is a dash pot. Controls the deceleration of the motor.

[Jason and Lund]

Here it is:
good luck, since it seems to be just one of two diaphragms on that engine,
I have no idea what it does or why...

[/url]

Thank you very very much!, Now I know it is diaphragm assembly, I can search it on the internet to learn its function. I guess it may control air or fuel.

[boscoe99]

Thank you very very much!, Now I know it is diaphragm assembly, I can search it on the internet to learn its function. I guess it may control air or fuel.

It does neither.

[99yam40]

sounds like it just slows down the closing of the throttle plates on the carbs a little

[Jason and Lund]

Friends don't let friends mess with their motors.

What is your service manual indicating as the means to adjust the idle RPM?

The copper coloured part is a dash pot. Controls the deceleration of the motor.

I bought a boat with this motor on an auction. I don't have service manual. I asked boatnet and want to buy 1997 model manual, the person chatted with me said the manual was not available.
Before adjustment the idle speed is 700 RPM, I increased to 800 RPM.

[fairdeal]

I don't have service manual. I asked boatnet and want to buy 1997 model manual, the person chatted with me said the manual was not available.

https://www.ebay.com/itm/11487175455...3ABFBMtNjY_tdg

[Jason and Lund]

Thanks fairdeal, I will buy it.

[boscoe99]

sounds like it just slows down the closing of the throttle plates on the carbs a little

You got it.

[boscoe99]

I bought a boat with this motor on an auction. I don't have service manual. I asked boatnet and want to buy 1997 model manual, the person chatted with me said the manual was not available.
Before adjustment the idle speed is 700 RPM, I increased to 800 RPM.

Interesting. Boats.net includes it in their listing of Yamaha service manuals. Yamaha shows the document as still being available.