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.

Honda usually has the model/serial, etc stamped into the block, not on the cowl.
 
I did find close to the model # you posted, rings are available oversize:
https://jackssmallengines.com/jacks-parts-lookup/manufacturer/honda-engines/engine/gx/gx390/gx390t2-qapw-engine-tha-vin-gcbdt-1000001/piston 
 
Did you check the ring end gap to see if their still in spec?  
 
 

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

I can't find your specific engine on-line.  
 
Can you please re-check and post ALL the #'s/letters on the block...
 
Also, where did you get the part # for your piston?  Is it stamped on there?

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.

Pictures

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

Seems like you got the stock sized rings (and oversized rings aren't available):
https://www.partstree.com/models/gx390-ut2-qaa2-a-gcbct-honda-engine-made-in-thailand-sn-gcbct-3000001-gcbct-9999999/piston-16/  
 
Did you stick them in the bore and measure end play?  

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.

Yep, I couldn't find the exact model # either, that's why I asked to repeat it. 
 
That link I posted is the closest model I could find to yours.  You may have to go to a dealer and see if they can find it (exact model and rings)...  I suspect they'll be looking at the same thing we are..
 
If no luck there, get new stock bore rings and check for end gap...  Not much else you can do.. 
New stock rings would certainly be tighter than what you currently have...
 
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