Cold Weather affect performance?

Does cold weather affect performance in a way that now I am getting terrible gas mileage?

I used to be able to go around 140 to 150 on the primary tank of gas.  Lately, the past few tanks, I am only able to stretch out about 110 miles before running out.

Could this be caused by cold weather?  And by cold (since I live in Southern California), I mean 40s and 50s (farenheit).

Barbara  

I dont know about the temp but I too have had a drop in mpg. I have been riding in 50-70 degree temps with a LOT of wind. It has gone from 42 mpg to 38 mpg. I think the high winds with a windshield on the bike has caused this change in my case.  

SoCalGal, you're talking about a 25% reduction in mpg. That is far beyond anything caused by your type of cold weather. However, it's always possible that you have overused the choke and partially fouled & carboned the chambers, requiring significantly more use of the throttle whenever the bike isn't fully warmed up. This is a fairly common problem with 2 cylinder engines. Most riders fail to adjust the idle stop screw for cold weather, which then requires excessive use of the choke.

Run some carbon cleaner through your chambers and replace the spark plugs. Then turn up the idle so that it idles at the factory recomended rpm when COLD instead of hot. That will enable you to turn off the choke after about 15 seconds and be able to ride the bike as soon as you shut off the choke. After about 10 minutes or so of riding, the idling will be creeping up as the transmission warms up, allowing the oil to warm up also. As the idle increases, simply reach down and turn it down when you are at a stoplight. That's why those idle adjustment knobs are right out where we can adjust them as needed. Just remember to turn it back up when you park the bike for the night :-)

My summertime (95°f+) distance to reserve is in the 145 to 155 miles area. When the temps drop into the 30's, it decreases into the 140 to 150 miles range for short rides. On the open road, it doesn't drop at all.

regards,
Joe  

Thanks Joe, very helpful information.