Smoking Kawasaki

[JPL]

Kawasaki FS481V-CS18
I will try to keep it short, This engine was smoking oil, checked compression was 60 psi both sides, leak down test valves tight, excessive amount of air coming from breathing tube and oil was black owner said he just changed it.
Decided to pull pistons and change rings, pistons were sloppy and showed wear on sides from pistons flopping. The pistons showed no blow by after the rings, but showed oil deposits on top of pistons. Changed pistons rings and oil rings new head gaskets. Reassembled and ran still smoking puffs, checked compression 90 psi checked leak down valves tight and still excessive amount of air coming from breathing tube and oil turns black within a short time. Checked pressure relief valve and it seems to be working as I can feel it pulsating when running. Both spark plugs are oiled fouled. I am at a loss now.
What my next step was to change the valve seals but not sure this is the problem.
Any help would be greatly appreciated.

[Luffydog]

Cylinders r worn out and prob out of spec. I would be guessing a short block is In need. Piston will always have carbon on top but In your case sounds like oil passing the rings. For the psi is still low. Did u replace valve seals? Or do the valves? Depending on your type of engine like model number might be able to bore and go with over sized pistons and rings. I would do a short block or new engine. Just my thoughts

[KE4AVB]

He well within the minimum compression considering the decompression release.

Service manual specs:
Cylinder Compression (MIN) 448 kPa (64 psi) @ Engine
Oil Temperature 50 ∼ 60°C (122 ∼ 140°F), Cranking
Speed 500 rpm/5 Seconds

But the cylinder does need measuring as I too think that the cylinder is worn out spec and needs oversizing. I think this since JPL has seen indications of piston slap; although, a rare seizing piston pin can cause this too. There is also ring landing wear and end gaps measurement that need to be done all of which are in the service manual.
http://www.mymowerparts.com/pdf/Kawasaki-Service-and-Repair-Manuals/FS600V-FS541V-FS481V-99924-2094-01.pdf

Cylinder Inside Diameter
Standard: 72.98 ∼ 73.00 mm (2.873 ∼ 2.874 in.)
Service Limit: 73.10 mm (2.878 in.) (Maximum diameter before oversizing is required)
Cylinder Bore Out Round Service Limit: 0.05 mm (0.002 in.)

Must be measured at the top, middle, and bottom of the ring travel area with two measurements at 90 degrees each other at each level. If any these are out of spec then resizing is required.

JPL when resizing you can't just use a flex hone to do this. It must be a rigid hone as a flex hone will only make out round and tapered conditions worst.

Note:
Cylinder Inside Diameter
Oversized is 73.48 ∼ 73.50 mm
Service Limit: 73.60 mm