GX390 Need help finding correct replacement rings.

Hello everyone and thanks for having me in your forum. Last year I bought a used pressure washer that had a GX 390 Honda engine. Are used the pressure washer a few times with no problem until I took it on a job that required me to get it down several flights of stairs. I assume that water got into the cylinder while doing so and it sat in there for a few weeks. When I started it, it was somewhat difficult to start and ran for about 10 to 15 seconds before shutting off. I was not able to pull start fast enough because it seemed like it had compression locked in. Anyway, I removed the head to see a little bit of rusty water and I’m in the process of replacing the rings. I honed the cylinder, even though it still showed some crosshatch. The rings were covered with some surface, rust and water so I figured I would replace them. I’ve meticulously cleaned every part and the top of the motor but have not been able to locate the correct rings. I’m wondering if this motor has been rebuilt and I’m ordering the wrong rings?

Model # on cowling sticker: GX390T-E1
Piston: Z5T90

Any and all help would be greatly appreciated as I am hoping to have my pressure washer. Running for a job in two weeks. Thank you and good day to all.

No I did not, I was hoping that the damage was minor cylinder wall abrasions that could be fixed with honing. They look worn and discolored.

Block model # GCBCT 2054731

Thanks for reply. Here are the numbers and location:

Engine block: QAA2 GCBCT-2054731
Piston top: Z5T90 B16Y5161A192
Piston skirt: HFA 6 Z5T

I just got Honda 13010-Z5R-004 rings but not sure if the will work or if I should order different rings…

I’ve tried attaching pictures of everything I’m talking about but it just things and things, but never attaches the photos.

I’ve tried to upload pictures with no luck…is there a trick to it?

Yes gap was .027” and the part number you referenced is not correct or does it matter if my engine number isn’t within the parameters?
GCBCT 2054731
QAA2
Piston: Z5T90

Im trying to upload pics of everything but unable.

And it continues…it’s been a while so let me start by thanking you for helping me. After reading thru my previous msgs you showed patience and knowledgeable guidance. Thank you.

So after talking to Honda this block did not leave their company with this piston. Looks like it’s had problems and that doesn’t bother me that much because when I got the unit it ran for 25-30 hours flawlessly and I was the reason it **** the bed.

Here’s where I need your advice. I have assembled this unit several times with the correct rings for this piston and my issue is this;

Every YT video I’ve seen shows the unit rotating very smooth by hand throughout the build. My unit seems to have a spot in the cycle where it’s sounds like some thing is grinding and it becomes hard to turn the shaft by hand.

- is it possible I have cracked the cylinder by sending a non-combustible liquid (h2o) thru the combustion chamber at rpm?
-is it possible that the bearing in side a block for the balance gear has a rough, rust or die bad spot in it?
-The piston does not feel damaged and everything fits snug while being assembled and I don’t see any cracks on the inside of the cylinder but I do see some hairline cracks on the outside of the cylinder head. I thought these might be normal.

Also, that engine is air cooled and water from the pump can only enter the engine thru the carb, not the block...
 
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Did the cylinder cleanup after honing?  If it's scraped bad enough, of course the piston will have extra friction, if not locking up.
 
Are the piston skirts smooth (and the rest of the pistons)?
 
Will the pistons, NOT bolted to the crank, lubed, move up and down somewhat easily/steady by them selves (push up and down by hand)?
 
Re the rod, I'd take it off the piston (if not visibly bent) and just lay it on a flat surface. Check and make sure both the small end and large end "space" is even when the rod is flipped over and re-checked. 
 
Re any bearings inside. If roller bearings are involved, you should be able to rotate them with you finger. They should be smooth, no slop (sideways or up and down).  A super close inspection of the cylinders should show if there's any cracks..
 
.Scott
 
Can you post some pic's? 

Hey ol friend, so I know what was causing engine to im m im scrape when turning it by hand. Connecting rod is bent. The piston is discontinued so should I buy the regular size piston and connecting rod since it didn’t damage cylinder wall?