I bought this mower less than 2 years ago and only run it around the edge of my yard so that my rider can make corners and such. It has less than 5-10 hours on it, I have always stableized the fuel when storing it for the winter. When I got it out last week to fire it up, it won't start. I checked the plug and have good spark. I dropped the bolt out of the bottom of the carb bowl and I have fuel at least in the carb. Don't know why it won't start. Any ideas??
(1) Probably bad fuel (even stablized fuel will decay eventually) or a stuck/sticking choke. Drain all the fuel from the tank and carb and get rid of the fuel in your external fuel storage can. Fill up with fresh fuel (ethanol free if you can find it).
(2) Your mower has an autochoke, which may be sticking OPEN, and that would cause a no-start condition. FYI, the HRX has a five year warranty, and if the autochoke is defective, it would normally be replaced under warranty. Some HRX2173HYA mowers were part of a Service Bulletin issued back in May, 2014:
Serial Number MAGA-2069723 through MAGA-2199999; if your mower is in that range, it may have sticking autochoke.
Find your serial number on the back rear of the mower deck, and read over this link for details on the autochoke:
Honda Autochoke FAQ
Drop me a private message with your full serial number and I can confirm the warranty status of your mower. Please include your name and address, and I'll update the record if needed. Honda asks for this in the unlikely event there is ever a product safety recall and needs to contact you.