Trouble adjusting carb; Temperature change; Fuel mixture problems

Hello,

After replacing a throttle cable recently, my engine really started bogging down and not running well. I took apart the carb and realized the carb adjustment needle was missing, which probably fell out after I installed the throttle cable. Amazingly, I was able to ride about 30-45 miles (with some decreased performance which I had attributed to a richer fuel mixture) before the engin wouldn't start anymore. After learning a little about carb adjustment, I noticed the missing needle. I replaced it from another engine I had around and it started immediately. I adjusted the carb a bit over the next couple of days and seemed to finally get it running about right a couple of days ago.

Then . . .
The next morning it started bogging down a bit, but did pretty well when it warmed up after several minutes of riding, then it ran as good on the way home. I adjusted the carb and it ran even better that evening. Then I had the same bogging the next AM, again with near normal performance on the way home. This AM, after changing nothing, I could barely get it started and warmed up. After about 10 minutes, it finally ran but not near full speed (up to 19mph instead of usual 23ish mph, but would bog at full throttle, which is not normal. The ambient tempeatures lately here in WI have been about 60 degrees in the early AM and about 75 degrees on my way home in the evening. Could this temperature change have something to do with my engine performance? Is there something else going on here?

FYI: I've been using Amsoil 32:1 while adjusting the carb, though Pablo said this was far too oily and told me to go to 50:1, which I was thinking about trying after this tank, especially if my performance doesn't improve.
My carb adjustment needle clip is as far down the needle as it can go, indicating, I think, that the engine is using a richer mixture. The spark plug is NOT oily. It looks rather gray and ashen, which suprises me since I'm using a rich mix and the carb adjustment is rich.

If anyone has any ideas about increasing my performance, I'd sure appreciate it!

Thanks in advance.

Eric

Thanks Norm, that will be a good thing understand as I continue to adjustments. I leaned out the mixture to 50:1 synthetic amsoil and moved the c-clip to near the middle to account for this and the bike seems to be running much better already, though it still bogs just a little bit at full throttle.

I haven't ridden it in varying temps yet. I'll have to see if temperature still affects how it runs. So, then, I might have to eventually change the jet to run the bike in colder temps? Would you expect to need a larger jet or smaller jet to run in colder temps?

I'm hoping to put studs on this bike and ride it as far through a Wisconsin winter as possible, with possible temps ranging from 30 degrees to about 0-10degrees (though I might wimp out at the lower end of the temps). Does this sound possible?