I think your initial diagnosis is correct. Same exact symptoms I had with a mower I purchased from my neighbor that had left gas in the tank which gummed up the carb. My main jet was partially clogged, and the pilot jet was completely plugged. It now runs perfect after cleaning. A new carb for my mower is $50, so I tried cleaning it. I also have an HRX217HXA mower, and I think the carb for that is about twenty bucks. At that price I might just get a new one, although I might not be able to stop myself from cleaning the old one to use as a backup. (Too much time on my hands)
Since your mower started having problems suddenly, its likely that some piece of dust, dirt, or whatever made its way past the air cleaner and is stuck in one of the areas you mentioned. It might work its way out, but I doubt it.
At least the carbs are cheap now. Not sure if the quality of the carb is why it went so soon. Dual air filters would be a nice preventative.
Believe it or not, but two days before the problem began I installed the two-stage filter from Honda's commercial mowers. I hope adding the oiled foam filter in front of the pleated filter will prevent future carb problems.
Parts to upgrade the filter cost less than $10 at the local Honda dealer.
I just ordered all the parts from jacks small engines for about $21.
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Upgrading the air filter to dual stage doesn't require replacing any gaskets. All that's needed is a grid that goes on top of the existing pleated filter, a foam filter (pre-oiled by Honda, btw) that goes on top of the grid, and a new outer filter shell to accommodate the additional filter thickness. That's all there is to it.That should take care of your problem. Did you order new gaskets, or will you reuse the old ones?
Ten bucks is a pretty good price for an updated filter. I thought about adding that to my HR217. Since my mower has been running okay as is I will probably leave well enough alone. But if I did a lot of mowing in dusty, dirty conditions I would definitely try out the upgraded filter.
I thought about using Seafoam as a treatment but worried about adding more alcohol to the fuel. I believe Seafoam has some alcohol and wondered if that might cause the alcohol content to exceed the 10% that is considered safe and start to eat away at the rubber gaskets and O-rings.
Instead I try to replace my fuel after 30 days, and drain the carb for winter storage. However, I messed up and forgot about the fuel in my chainsaw and left some in it for several months. Since I do not use it much, I tend to forget about it. Looks like I may get some practice cleaning out a two stage carb :frown: Oh well, live and learn.
In the category of too-much-information, I suspect Honda sells foam filters pre-oiled so customers know how much to apply when they clean and re-oil the filter.
May sound like a "duh" statement, but not everyone knows the correct amount of oil to use. One other tidbit is Honda no longer sells Motul filter oil, but Motul is available at motorcycle shops, as are other brands.
My parts guys says the foam air filter elements are usually shipped dry, and should be oiled before use. Note the plastic grid that goes between the foam and paper elements is a stand-off, so the oil does not get absorbed by the paper filter.
Honda does indeed sell genuine MOTUL oil for foam air filters (it is branded with the Honda logo). It's part number 08207-MTL-100, 4 oz bottle retails for $7.56. Google the part number or use this link to find a local dealer:
Find A Honda Dealer