Originally Posted by MitchG
The answer is no, it will not contribute any measurable warmth inside the helmet. That being said, to keep your face warm you must minimize air flow inside the helmet as much as possible(read good sealing in the neck area). Unfortunately, now that you've stopped the air flow and your face is warm, your shield will start to fog. This is why you need
a heated shield.
Just noticed you are using a breath mask. These things are a must, and work unbelievebly well. Thought I needed some new ones so I went to nofogusa.com and low and behold, they have a heated version now: www.nofogusa.com/Optional%20Heat.htm
Well, the HJC IS-Max with pinlock, breath mask, and chin curtain all in place actually do take care of all of this. Problem is the chin curtain folds up on the breath mask, which is how i've been using it. I thought there were other vents letting in air, but after your comment tried unfolding the curtain to fully cover the bottom and it seemed to stop the airflow entirely. Unfortuantely it takes a while to futz with the curtain every time the chin bar is lowered and it frequently pops out requiring the entire helmet to be removed for replacement.
With everything in place though, the only thing that fogs is the internal sun-shield occasionally...