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Els 40H777 . One cylinder has 160 psi clean plug other 65 and plug is oily. Could it be valve lash? If not im guessing head gasket or rings.???

Need to perform a leak down test to isolate issue(s). Otherwise you are guessing and will start firing parts from the cannon. How many hours/age of engine?

I lay odds on it being the #2 Cylinder being worn out. I have seen several Briggs OHV twins with #2 shot.

This is cyliner on left. The intake valve lash is .003 the exhaust is .029. Leak down test wont distinguish between head gasket and rings will it? Both going to blow into crankcase ,no?

junkman108 said:

This is cyliner on left. The intake valve lash is .003 the exhaust is .029. Leak down test wont distinguish between head gasket and rings will it? Both going to blow into crankcase ,no?

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No but a head gasket is cheap and it only takes about 1 hour to change
Cheap and nasty test for rings is to work the throtle valve by hand
Worn rings will progressively blow more smoke as the throttle is opened and leave an oily deposit on the spark plug
A leaky head gasket will not leak then suddenly dump oil into the cylinder
If it is in the mower engage the blades
If you get some knocking and white smoke as the baldes start to spin and clear up then that is a head gasket
If it just blows smoke and continues to do so that is the rings .

I put air in cylinder removed push rods. Air coming from dipstick and where push rods come from. I figured no way to distiguish which one.

Why that happen and why its happens in cyl#2 only? Look like rings broke?

Looks to me, blury pic and all, that the engine was over heated. Look at the aluminum that was deposited on the bore. Or is that some plastic??? Can't tell from the picture.

Has the engine cover ever been off and checked for clean and clear cooling fins? Post a picture with the engine cover off.

slomo said:

Looks to me, blury pic and all, that the engine was over heated. Look at the aluminum that was deposited on the bore. Or is that some plastic??? Can't tell from the picture.

Has the engine cover ever been off and checked for clean and clear cooling fins? Post a picture with the engine cover off.

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Yeah it was filthy. I slapped it back together ot still has same 65 psi with used head gasket going to run it until it blows or makes it to fall. I got a kohler command cv20 in storage.