Do you turn the air screw (the one under the plug) in or out to lean it some?  

I am running slightly rich (mild gold pipe) and I want to lean it a bit at a time with a week at each partial turn setting until I find optimum for my particular bike.

Oldfeller

Conditions at start of experiment -- Stock bike, 2002 year LS model at 4,000 miles.  Half spacer and uncapping air screw mods performed at 1,700 miles, highest idle speed discovered at 2 1/4 turns out and idle adjusted to circa 1,000 rpm as per general list recomendations.  

Top speed 87 miles per hour, gas mileage runs between 46 and 52 mpg.  Pipe runs a mild gold -- takes at least a week to develop fully after a pipe cleaning with Blue Away.   One very small section on inside of bend gets a tiny bit bluish, rest turns gold.  Mild gold section also develops in exhaust pipe just short of bevel zone at end of pipe.  Oil is Mobil 1 Clean 5000 10W40.  Valves are due for adjustment soon.

Pipe cleaned with Blue Away to dull chrome neutral color.  Air screw reset to 2 turns out.  Idle readjusted.

Air screw setting experiment starts now.

Oldfeller

No improvement in performance noted for 1 3/4 out setting.  Pipe is neutral with slight purple/gold hints with blue patch on  bottom of pipe right beside head exit and similar sized blue patch on outside of curve (in line with the patch on the bottom inside edge).  Must be some sort of gas flow thing going on inside the pipe to provide the localized blue zones, but their presence says I am getting back towards the lean side again.

Gas mileage is worse at 44.84 MPG.  There is no improvement in top end and accelleration seems to be no better (perhaps worse).   If anything more off-idle throttle twist is needed to get the same reaction as I am used to seeing.  

Bike is spitting and backfiring about like "normal", so a slight decline in backfire action for this setting compared to 2.0 turns out.

I'm going to continue one more quarter turn just to verify I have really crossed my optimum point and indeed am going the wrong way now.  

Pipe cleaned with Blue Away to dull neutral color, air screw turned to 1 1/2 turns out.  Idle speed had to be increased again after this change.


Oldfeller

No, in this experiment I am trying to see what the running characteristics are for each setting, so I just provide a correct idle speed after the adjustment is made.

Tuning the air screw to provide the best idle speed (or judging the central span of best idle speeds by splitting the difference between the  in and out choke points) yeilded a slightly rich condition on my bike when I first did it according to general list recommendations.

Now I am doing it emperically by slow stages, seeing the mileage and operating characteristics for each stage and NOT considering the effects on idle speed.  If I find good operating characteristics, I will give it the idle required to live there.

I think we put on blinders when we just go for a maximum or "most central" idle speed -- when what we really want is best accelleration off idle up through mid range, the best gas mileage and "most neutral" pipe color.  

Idle speed is just another very easily made adjustment that can be made AFTER we get the things that are really important to us.

Oldfeller

Pipe colors -- heck we can't even keep the same interpretation going on what causes which color.  

Historically, I have always heard gold was rich and blue/purple was lean with gold being   "rich/cold" and blue/purple being "lean/hot".   You heard it the other way around.

Go figure.

Now here's another myth buster for you -- I can't find that magical neutral chrome color existing in between the gold and blue ranges -- what I do find is sections of each showing up on the same exhaust pipe !!  

I got myths falling all over themselves over here ....

What I can suggest is using maximum or "middle" idle speed alone to make decisions isn't refecting all the post mod variables on a stock bike very well.   Max idle speed was too rich on my bike.   Middle would have been closer, but still a bit rich really.

Better running characteristics existed BELOW the point of maximum idle speed on my Savage (and perhaps on yours as well).

First, write down what you consider important to you.  I value good accelleration, best gas mileage, no severe spitting & backfire action and a good pipe color in that order.  Then test for it, writing down your results as you go.

You will get closer using this method than trusting an idle speed to magically tell you the whole story.

Oldfeller

As anticipated, leaner didn't work better -- it ran worse.  

Going back to the best zone (which was 2 turns out) I started turning it in by the 1/8 turn.  Currently best acceleration and best spitting and most OK gas mileage exists at 1 7/8 turn out (44.28 MPG) and the pipe is running two very small blue patches and the rest of it is turning very slightly gold.

I think this is about as good as it gets (and honestly I'm tired of messing with it).  

I have no proof that this air screw setting actually changes due to the season as has been mentioned by some, but I will be watching out for that sort of thing over this upcoming fall/winter changeover.

Oldfeller

Isn't the BMW pipe a small diameter single-walled pipe?   Maybe Germans consider pipe coloration to be a necessary indicator of motor tuning and wanted it to be something that must be clearly visible to the rider?  A cultural German techo-mildset attribute, in other words.

I never noticed the old Honda 550 Guzzi style bike bluing its pipes although it too took a pretty sharp bend right out of the head.  Once again, the Japanese generally don't like blue pipes and go for double wall construction.

I have had several Hondas and a Yamaha that didn't blue at all, nor did they turn gold either.  Construction on both was double wall pipe and the diameter of the pipes were considerably smaller since they were twin cylinder bikes.

Is the pipe on the Savage a double wall construction?  If so my isolated zones of blue may be inner and outer wall touch points where heat is being directly transferred between the layers of the pipes.  If not, then the location indicates flow points where hot gas flows directly against the pipe walls (this is how I interpret the blue spots since they make sense that way).

I dunno ....  who has cut a Savage header pipe to shorten it and knows the construction details?

Oldfeller