Recently purchasing a HPI MT2, I decided with the packed snow it was OK to run the truck through its break in procedure. I've run about 4 tanks through it now and would normally begin to start tuning for more power. I'm worried though with the 0 degree weather, is it better to keep the truck on factory "rich" settings versus leaning it out? Also, by leaving it rich will that do any harm in any way? You opinions are greatly appreciated.

Thanks!

Your motor should have come up to at least 230 degrees every time you ran it and then cooled down or you haven't really done anything as far as the break in is concerned

I agree with rclynx it needs to get up to higher temps that you can't do in the cold. The heatsink is there to dispurse heat in hotter weather so just think how efficient it is in the cold. The best option is to wait till it warms up, I know its hard to do! Or if you absolutely have to attempt to break it in you'll need to cover the head with Aluminum foil or something else to retain some heat, but not too much or you'll overheat it.

Or you can take a sock, or tin foil and wrap it arounf the heat sink. This will act like a blanket and will help raise the temp of the engine, but check the engine temp often. And as said if the engine hasnt reached high enough temps then you will due more damage to the engine then anything really.

With the truck taped up and aluminum foil over the heat sink, I'm running around the 230 - 240 range, so by that I would think I'm ok.

Yes as long as the temps get above 220f and stay under the 270 to 280 mark then your fine

And dont lean it out to get temps up... make sure you leave it as close to factory settings as possible for break in... just wrap up the head and keep the body sealed. I broke in a motor this winter like this and had no problems! Have fun!