Be very careful with your test runs and don't lean seize the new cylinder & piston.
I think the factory tuned these units rather close to being dangerously lean.
The units I have were ALL damaged by that lean jetting from the factory.
So be mindful of the carb tuning. You may need to up size the main jet.
Along with verifying that the throttle controls are all in order,
I'd be looking closely for anything that could be an air leak.
You probably should check carefully items #8 #10 #11 in this link.
https://www.jackssmallengines.com/j...wers/ebz8500-sn10200101-and-up-2014-04/engine
Don't forget to check the seal on the face of the carb body.
Just a quick reach into the pile of lean sized units sitting here.
A couple of quick snapshots, but You can see that item #8 (carburetor insulator) took a good bit heat and began to melt.
The dark stuff sort of hanging into the openings is the plastic that oozed out into the ports.
The gray stuff that sort of resembles a sprinkling of salt, is actually aluminum splatter from the the piston dome/crown.
The operators ran this unit until it melted a hole in the piston.
Sorry the pics aren't properly lit, but I just wanted a quick image to post for now.
Are you familiar with the accessing the low speed mixture needle adjustment?
https://www.walbro.com/wp-content/uploads/2016/01/WYAseries.pdf
This pdf shows where the need is located. Look at page 3.
The number 17 arrow points to where the needle is located down in the middle of the throttle barrel.
You probably need to remove a plug or bit of sealer, in the top, to access the head of the needle.
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Forgive me for my missives being even more fragmented than usual.
I'm a bit sleep deprived at the moment (stormy weather has stirred my arthritis & migraines). I'm not in the direct hurricane affected areas, but the barometric swings still reach out surprisingly far.