Air Mixture Screw Inner Cylinder Settings

[twr1776]

I have seen mention here and there of setting your inner two cylinders slightly richer than the outers.

Any pros, cons, opinions? If you have yours set up like this how much additional in turns do you use and how have your plugs read after changing? I am referring in my case to 850 & up two valve motors. Any thoughts are appreciated.

 

[Turtleface]

I have seen mention here and there of setting your inner two cylinders slightly richer than the outers.

Any pros, cons, opinions? If you have yours set up like this how much additional in turns do you use and how have your plugs read after changing? I am referring in my case to 850 & up two valve motors. Any thoughts are appreciated.

Most of the time, at least from what I've read, the extra fuel in the middle cylinders is provided by a larger main jet, not through the mixture screw. The idea is that the inner pots get less air flow, and need the extra fuel to help keep cool. Some GSes came like this from the factory as well. I don't think plug coloration would change terribly much, you'd still want tan plugs either way, the two inside plugs might be a little darker, but still within range.

 

[ddaniels]

I've heard of setting the two inner cylinders slightly higher during syncronization than the outer two, but nothing about a difference in the air mixture settings.

 

[Guy]

Up a size on the main jets, or a slightly lower vacuum at idle on the inner two cylinders will help them run a little cooler, but changing idle jets is probably a waste of time.