[savgaboy]

I have a 2000 model Yamaha 100 4 stroke. Can someone tell me how to adjust the 3 screws on my carbs? These are the 3 screws with springs on the outside of the carbs. I think they are for the air fuel mixture.

[boatguy823]

I would highly advise you not to touch those screws. They are for adjusting the vacuum settings for those carbs. You cannot adjust them with out a vacu-mate or other such tool (it is a tool used to measure the intake vacuum) Improper adjusting of those screws WILL cause your engine to run very poorly if at all. Let someone qualified do that.

[triumphrick]

In ten years i never touched the screws on my Yamaha 90....if fuel related problems, you need to be checking filters, screens, water/fuel separator etc. I would not expect those screws to be adjusted without the proper tools and technique.

[stubbsboogie]

BE Careful!!!!!

I have the same motor and was about to post a follow up thread. Those carbs are tempremental. And expensive! I just had to replace my #3 carb to the tune of $400 before instal.

Reason why- the previous owner tried to monkey with them in his garage. Take it to someone qualified and let them do it, will make things much easier.
Good Luck

[savgaboy]

Thanks, I am carrying it Monday.

[rodbolt]

make sure on monday you look at the techs wall for fuel,electrical and 4 stroke certs,
even ask to see this wondurous techmate-vacumate tool.
if ANY are missing please take a mulligan and go find a real shop.
and the F100 has 4 carbs.
air fuel screws are hidden under a brass plug from the factory.

[swantzilla]

What if you had to take the carbs off for cleaning and rebuilding? How do you set them up afterwards?