Yepp, been there done that. One time I could not get my YS 110 going during very cold weather, I took my thermos with hot coffe and poured some over the cooling ribs and it instantly fired right up. It doesn`t take alot of heat to help out. But I prefer to heat myself with my coffe so I use a torch on my engines now.

As you said, common sense and care must be used as well, or a bonfire could be the result.

Edit: bad grammar[:@]