Does that smell means bad cn ratio? Do I need to add more carbon?
I don't do hot composting, mainly because I live in northern Minnesota and for a good 6 months out of the year we are covered with snow and low temps. Having said that, if compost smells bad, it's almost always too much greens. I'd mix in more carbon anytime you smell something off. If someone has other advice on hot composting, I'd be interested in what they have to say.
I mainly compost in the chicken run, and it never smells like anything other maybe a wet a forest floor after a good rain. I dump in all kinds of grass clippings in the summer, but the chickens will mix it in with the existing compost litter in the run so I never have any bad smells.
FYI. this winter, I started using paper shreds I make at home as my chicken coop deep litter. All that carbon (paper shreds) will make its way to the compost. It's amazing how much paper I get to shred every week (bills, junk mail, newspapers, food cardboard boxes, etc....). Shredding the junk paper saves me time and effort from hauling it to a recycle bin or center, plus, the chickens get to use it as litter in the coop, it will get composted outside in the chicken run when I clean out the coop, and the compost from the paper shreds will eventually make its way to one or more of my garden beds to grow people food. If you need carbon sources, don't overlook all that junk paper you might be throwing out.
Bonus tip: I got 2 of my paper shredders from our local thrift shop. Paid about $3 for a 5 sheet shredder and about $5 for an 8 sheet shredder. Both would have sold for about $80 each new. Easy, and cheap, way to get into shredding paper to see if you can make good use of the paper shreds. Certainly easier than ripping heavy cardboard by hand.
Just like the old doctor jokes, if it smells bad when you turn over a hot compost pile, don't turn over the hot compost pile! Let it cool down a bit as intended.
