F60 - adjustment of A/F screws

[exeter27]

I have a 2004 Yamaha F60 (F60TLRC). I have the Yamaha service manual along with the supplementary manual (basically F50 manual + differences for the F60).

This past fall, during winterizing, the engine was 'sneezing' ever so slightly. Over the winter, I completely disassembled the carbs, cleaning them in a heated ultrasonic bath. That included removing the brass plugs and the underlying A/F screws (after noting number of turns for each carb) This spring I re-installed the carbs and it started within half a crank of touching the key. Sounds great...but not quite. The sneeze was still there. And lifting the high idle lever can make it worse.

I looked in the manuals and the only 'link/sync' I can find is related to carburetor synchronization. Ok, I've done that before on many motorcycles - so that's in the plans (except that my Motion Pro sticks only have the 5mm adapters and my outboard uses 6mm). I'll get that remedied today.

But, my real question relates to the screws under the brass plugs. I hesitate to call them fuel mix or air mix because other posts from Rodbolt suggest these really only alter the amount of a prescribed A/F mix determined by various jets in the carb. Regardless, I can't find anything in the service manual to adjust these screws. Did I miss it? If so, what page is it? My manuals are LIT-18616-02-67 (62Y-28197-1F-11) and LIT-18616-02-68 (69W-28197-1F-1X.

How do I adjust these screws? thanks!

[exeter27]

Ok - I found the 'link' part of the link/sync procedure in the manual. But, I still need help on the proper way to adjust the screws under the brass plugs. My service manual doesn't reference them....

Thanks in advance.

[99yam40]

most have them listed in the spec sheet as pilot screw setting.
turns out from lightly seated

[boscoe99]

When the EPA tamper resistant plugs were implemented the SM stopped giving advice as to how many turns the idle mixture screws were to be screwed outward. Yamaha now tells the mechanics to turn the screws inward, before the carburetor is disassembled, and count the number of turns that it takes to get them to be lightly seated. Then use that as the setting once the carburetors have been cleaned.

In the good ole days before the EPA came along the specification for those screws was 2 and 3/4 turns outward from being lightly seated, plus or minus 1/2 turn. This still applies to your motor.

Ethanol in the gasoline will cause the air/fuel mixture to be a tad on the lean side. This might be resulting in a lean sneeze that you are experiencing. Try turning the screws outwards, as much as an additional 1/2 turn from the base setting. Hopefully, this will solve the problem. If not, you may want to try installing an oversized idle mixture jet.

What Yamaha does not tell anyone is that earlier F50's used a #42 jet. Later F50's/F60's used a #39 jet. When the smaller jet came into use more folks had troubles with getting their motors to idle properly. If it were my motor I would not hesitate to install the #42 sized idle mixture jet.

With respect to what the idle mixture screw does, there is some apparent confusion. I suspect that it is just a matter of words. Rodbolt says that turning the screw outward, opening the passageway a bit, just allows more of the same air/fuel mix to be added to the carburetor. I don't disagree with this. But what is being allowed to flow through is a very fuel rich concentration. Adding more of that super rich mixture results in the air/fuel mix seen in the combustion chamber to be richer than it otherwise would be.

That's my story and I'm sticking to it.

[99yam40]

do these F50 motors require multi channel Manometers to get them set properly?

[boscoe99]

do these F50 motors require multi channel Manometers to get them set properly?

Highly desirable. But gauges will work.

[exeter27]

Thanks Boscoe. I recorded the number of turns from closed for each - so I'll use that as the base adjustment. If I recall correctly, they varied quite a bit from carb to carb. I know these are factory set because the plugs were in place.

It's too bad that Yamaha decided to omit the procedure to set these pilot screws.

I appreciate your information and will try opening them up to see if I can get the sneeze to disappear. I don't know which jet I have - and I really don't want to disassemble the carbs again. But, if the sneeze persists - I'm going in! If it's the smaller jets, they'll be replaced with larger ones. Stay tuned.

[boscoe99]

Thanks Boscoe. I recorded the number of turns from closed for each - so I'll use that as the base adjustment. If I recall correctly, they varied quite a bit from carb to carb. I know these are factory set because the plugs were in place.

It's too bad that Yamaha decided to omit the procedure to set these pilot screws.

I appreciate your information and will try opening them up to see if I can get the sneeze to disappear. I don't know which jet I have - and I really don't want to disassemble the carbs again. But, if the sneeze persists - I'm going in! If it's the smaller jets, they'll be replaced with larger ones. Stay tuned.

Yamaha has decided that the screws are not to be messed with. Thus the EPA plugs that are intended to keep anyone from gaining access to the screw in the first place.

Back in the day, before the EPA, the service manual provided details as to how to go about setting the screws.

[pstephens46]

Just like Boscoe's chainsaw.

[boscoe99]

Yes. But if there is a will there is a way.

Might be drilling and pulling the plugs to gain access to the screws or it could be buying a specialized tool to adjust the non-adjustable idle mixture screws.

The EPA must think that we are fools. They do think that we are fools.

[pstephens46]

Look at the people who have been running the EPA the last 30 years

[exeter27]

Well, I got my Carbtune directly from the manufacturer in Ireland yesterday. Today I connected it up - and sync'd my carbs. Now they are in good balance - but I still had a bit of a lean sneeze.

But, an added bonus of the carburetor synchronizer is that it showed very clearly which cylinder (in my case cylinders) were sneezing. I slowly tweaked the jets for each (counter clockwise to richen) and got rid of the sneeze.

Here's the interesting part for me. I removed the brass plugs - so I know that part of the carbs was never touched. They were 1.5, 3+, 3.25, 1.25 respectively for cylinders 1 through 4. And yup, it was 1 and 4 that were sneezing. I can believe the difference (from the factory) between the carbs.

But, the engine now idles up smoothly with no sneezing. I'll get it out on the water soon and hope it goes right up to WOT nicely.

So, if you have a lean sneeze, a carburetor synchronizer can show you which carb(s) are lean!

[Jason2tpa]

I slowly tweaked the jets for each (counter clockwise to richen) and got rid of the sneeze.

Here's the interesting part for me. I removed the brass plugs - so I know that part of the carbs was never touched. They were 1.5, 3+, 3.25, 1.25 respectively for cylinders 1 through 4. And yup, it was 1 and 4 that were sneezing. I can believe the difference (from the factory) between the carbs.

Full disclosure, I had no knowledge of a carb tuning device. Did some research after reading your post and it seems pretty nifty. Might be time to add another device to my tool box.

You stated you tweaked the jets by turning counterclockwise. I'm a little confused. Are you saying you opened the brass plug for carb 1 and 4 and turned the air adjusting screw?

I looked at your engines carb schematic below so I could follow along to your detail. Did you open plug #40 and adjust screw #20?

2004 F60TLRC Yamaha Outboard CARBURETOR Diagram and Parts

[exeter27]

jasontpa - yes, last fall I had removed the brass plugs as part of a full carb cleaning. I recorded the factory settings as described, then fully disassembled the carbs for full cleaning. That happened over the winter.

At first startup this year, it ran ok - but had a lean sneeze. There was no way for me to know which carbs were involved. I had no idea that the Carbtune would also show which cylinder had a sneeze (vacuum i.e. rod drops during a sneeze).

While Yamaha calls these air screws, I'd suggest they are fuel screws. I say that because turning counter clockwise makes things better - thus meaning that it lets more fuel in.

[99yam40]

Jason, make sure the motor you want to use it on has a place to hook it to, before buying it.
not all motors have places to hook it up to