Question on Air Mixture Screws

[brveagle]

If you look at my drawing, what constitutes "one turn" of the air mixture screw. A buddy and I were discussing this and disagreed.

Is what i have drawn up, one turn, or a half turn.

Thanks

[tkent02]

Half turn.

[mark]

Half turn.

Yup, that's a 180 degree turn. A 360 is what you want for a full turn.

[brveagle]

Good to know. This whole time, I've been only turning my air mixture screws out .5 - .75 of a turn. Maybe thats why my idle hangs

[Nessism]

Good to know. This whole time, I've been only turning my air mixture screws out .5 - .75 of a turn. Maybe thats why my idle hangs

If you are tuning a 1980 550E you want to be somewhere in the range of 3 - 3-1/2 full-turns open.

[Suzuki_Don]

If the mixture screw is too far in (ie, not turned out the required number of turns) will it be too rich or too lean.

Cheers

Don

[baldbastard]

If the mixture screw is too far in (ie, not turned out the required number of turns) will it be too rich or too lean.

Cheers

Don

In lean, out rich.

[Nessism]

In lean, out rich.

This is true for the Mikuni BS series (CV type) carbs - generally found on 1980 and later GS bikes. Suzuki used VM series carbs on the early GS bikes and for those there are two screws: a "fuel" screw and an "air" screw. Out on the fuel screw richen's the mixture but out on the air screw leans it. It's important to pay attention.

[Suzuki_Don]

Thanks Nessism. I forgot to mention that I do have VM type carbys, but I guess you suspected that. If its too rich at idle which screw do you adjust, fuel or air and where are they both found. There is one on the air filter side of the carby, which one is this and where is the other one.

Cheers

Don

[waterman]

As was stated, that is a half turn. Even so I find it easier to remember when checking how many turns out to count each half turn as one. Then when resetting I can simply set it back. I see that this may be confusing, but it works for me since a half turn is about all that I can do with a screwdriver without slipping out of groove. Plus I think it is easier to keep track of turns. Who knows...

[Nessism]

Thanks Nessism. I forgot to mention that I do have VM type carbys, but I guess you suspected that. If its too rich at idle which screw do you adjust, fuel or air and where are they both found. There is one on the air filter side of the carby, which one is this and where is the other one.

Cheers

Don

Hey Don,

The air screws are visible from the top - located on the right side of the carbs on my '79 550. Turn the screws out to lean the mixture. If you get more than two turns or so, you may have to screw IN the fuel screws, which are located on the bottom of the carbs in the front center.

Hope this helps.

[Suzuki_Don]

Thanks Nessism. Does the float bowl need to be removed to access the fuel mixture screw or is it accessible from outside. BTW my bike is a '77 550.

Thanks again.

Don

[Nessism]

Thanks Nessism. Does the float bowl need to be removed to access the fuel mixture screw or is it accessible from outside. BTW my bike is a '77 550.

Thanks again.

Don

They are accessible...sort of, you need a very short screwdriver and the inner carbs are going to be a real pain to reach (haven't tried to adjust them yet...but need to since my bike is very cold blooded).

[Suzuki_Don]

OK that is good information Nessism. I will have a go at the air screws this weekend. I get a good wisp of black smoke at startup. I think it could be because the 4 into 1 system that is on the motor is a bit more restrictive than the standard system. It is a very quiet 4 into 1 system, not at all noisy like you would expect from a 4 into 1 system. Also the air screws are only backed out from the bottoming position by about 1 1/4 turns.

Cheers

Don

[the_journeyman]

I use an offset screw driver to access stuff in placse like that. Works most of the time ~

JM