YT125

Thanks everyone

Hi all. Does humidity affect our engines? The reason I ask is I have a Yamaha YT125 Tri-Moto (DT125 engine just detuned a bit) and I've noticed on humid days that it runs a bit different. The humidity has been between 70-80% for the last month so. When it is humid it doesn't like to idle and will only start if the throttle is slightly cracked open, and above 3/4 throttle it likes to cut out and just doesn't seem to have the power it usually does. On a non humid day it day it will start right up and idle all day, and doesn't cut out above 3/4 throttle. At full throttle on a humid day I can hear it struggling to suck air. It's all stock running the factory air box and filter with a Mikuni VM20SS #25 pilot jet #200 main jet. If anybody has any ideas it would be great. Thanks