[john651]

This engine runs fine at any speed over idle. At idle it runs rough and requires choking or more throttle to keep it running. Idle improves slightly when the engine has warmed up but is still rough.

Engine and fuel tank are properly winterized each year, filters changed and the problem developed near the end of this winter season in Florida. No visible dirt or water in the tank or filters. Plugs and fuel pump were replaced. Carburetor cleaning has been suggested and I am ready to start. I purchase the gaskets and printed the parts diagram but my friend’s Yamaha technical manual did not show any carburetor disassembly instructions or settings.

1. I was told to pop off the linkage and not change the linkage adjustments.

2. I found this tip on the idle adjustment mixture screws. Before taking one out, gently screw it in while counting how many turns you go until it seats (very lightly) (be very gentle). Count every 1/2 turn until you get a final count

3. I am looking for any other tips and settings especially on the main jets.

Any help will be deeply appreciated.

[rodbolt]

no worry with the main jetting, your issue is with the pilot fuel jets, remove the carbs, remove the fuel bowls, clean the bowls and the jets and reinstall with new bowl gaskets.
if you place the same needle/float assy back in the same needle seat your float adjustment wont have to be monkeyed with.
correct A/F screw setting is 5/8ths of a turn from lightly seated.

[john651]

That is exactly what I needed. Thanks for the help. Will clean them on Saturday after the rain stops in PA.