My first post, I had done a lot of useful reading on the site, thanks to all here!! Hope I am following proper protocol. I did make a donation, if that helps  

2014
Bought it 4/17 with 2,500 on it, as of 11/17 it has 6,800 on it. I love riding it.
I am able to run pure non ethanol gas in it about 50%-75% of the time. Closest source is 25 miles away.
I changed my oil to Mobil 1 V-twin about 500 miles ago. Even with my lousy hearing I noticed a little less clatter.
Completely stock except for jetting noted below & Raptor petcock.

My mechanical expertise is fairly limited. Oil / filter, battery changes and such. 40 years ago I used to adjust the valves on my Datsun 510 and my Dodge Slant 6 & do basic tune ups on them. Beyond that.....

I had a local mechanic rejet my carb a while back (actually, he drilled them out) and I've been satisfied with the improvement. With real gas, popping is now essentially non existent, and pretty minimal with ethanol gas.
Weather has started getting cool here.

Recently I put a new HiFlo air filter in (old filter did not look too dirty) and drained the "puke tube" for the first time since I acquired the bike, It drained a fair amount of coffee brown looking liquid. I guess I waited longer than I should have. Also, around this time I switched from StaBil 360 to Lucas fuel stabilizer/ethanol treatment.

The point, finally:
So about this time the bike seems to act like it is too lean, defintely a different feel. I had the same local mechanic, more of an old school guy, been at it for years, take it for a ride & that was his opinion - running lean. But he thinks it's because the weather is getting cooler. Doesn't seem to me like it has cooled enough yet to lean the bike out that much. Bike still idles fine, no low throttle surging like I had before the jetting. Although it is a cold blooded machine. I take it around the block a few times before getting on the road.

While it doesn't seem logical to me, I wonder if either one or a combination of both the new new air filter and maybe doing the puke tube drain later than I should have are involved? Anytime the bike starts running/feeling different there has to be a reason. The Lucas fuel treatment is highly rated, does anyone here have any experience with it?

Welcome to the forum. In order for us to help you, we will need some additional information. Can you describe what you mean by lean? Is it unridable lean? Is there a lean bog as you go from one circuit to another? Is there lean surging? Just what are we talking about?

The bike is lean from the factory. Has it been previously rejetted? Are you using an aftermarket exhaust?

KY Bluegrass wrote on 11/18/17 at 18:25:09:

By lean I mean that each detonation of the spark plug seems to be harsher, more pounding. Also, the bogging you get when revs are too low in any gear seems to be more pronounced. This came on more suddenly than gradually.

Detonation is a condition similar to preignition, and can damage an engine fairly quickly. It does result from too lean a mixture. But I think you just chose the wrong word. I think the word you wanted to use was "combustion" or "ignition". If you did intend to use the word "detonation", I'd stop riding the bike.

What is the throttle position where you experience the lean bog? Is it passing through 1/4 to 1/2 throttle, or from 3/4 to WOT? When you had the bike jetted, do you happen to know what jets were used and the needle position?

What I mean is that the firing/ combustion seems a little more intense. The bogging I refer to is what happens when you give it more than a little throttle when the revs are too low in any gear. Like if you shift up too soon. The bike runs best when I wind it out at a little over half to 3/4 throttle and get the revs up decently before up shifting.

I don't know what he drilled the jets out to, he said he has it written down somewhere. He did say he raised the needle.  Like I said, the bike has run good since the jetting changes, it just been in the last several weeks that it is this way. Sorry I am not doing a better job of describing it.

Batman:

I am at 650-750 feet elevation.

The new air filter is a HiFlo HFA  3608. I didn't change the box or anything, just swapped out the filter.

I first brought out the fuel mix screw a full turn. Couldn't see any change. Then I re adjusted down to where the idle began to slow and then back out 1/2 turn.

I always run 87 octane. About 1/2 the time it is E10 and the other half it's 100% gas. Last 3 or 4 tanks have been real gas.

As I said, I did change from adding Sta Bil 360 to Lucas recently.

Mechanic said he was afraid if he jetted it any richer that I'd be fouling plugs come summer.

KY Bluegrass wrote on 11/18/17 at 19:36:38:
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I'd probably go with what he said (or buy a fuel injected bike. )  If it bothers you that much, rejet now and plan on rejetting again when it gets hot out next summer.  

You'll never jet a bike to run perfect year round.  My bike runs best between 50-70 degrees, a little too rich above 80 degrees and a tad lean below 50.  But it's ridable year round,  and actually runs stronger when it's towards the lean side of things.

The only other thought I have for you is make sure you slide is perfectly clean.  If it's not perfectly clean, or the coating is worn off, it won't respond quickly to the vacuum created when you open the throttle (plate).  This will cause a momentary lean condition or bog.  I replaced my worn slide this summer and it made a noticeable difference.

You really don't need sta-bil or lucas, if your running good gas most of the time ,you only need it if the bike is being put away for the season,as you keep using these they may well be building up in your gas tank(no body ever runs their tank completely empty)so after months of use there may be a much greater percentage of additive to gas  in your fuel tank than you  realize. When they burn they don't make hp ! I'd dump your tank ,put in new fuel (only) and see if the bike returns to normal,it's not hard ,and costs little.