Honda's and Yamaha's are setup lean, on the pilot curcuit, when new. This is for emissions. I have noticed the mains are maybe slightly rich. The idle mixture scew is fast and easy, to fix a lean misfire, when the engine is cold. And that's the key, if it only does it when it's cold, then it's a lean misfire. Another benefit of turning the mixture scew richer, or going up in pilot size, is the starter works much less. Have you checked the price of a Honda starter lately? $350 for one, I'm doing right now!

 

I've noticed the same thing about the low and high rpm carburation wildman.