Head gasket, maybe???

[38racing]

I had a single cylinder briggs ohv that ran fine with no noticeable smoke but kept consuming oil. Due to reputation I pulled the head and found bad head gasket.

[Arkie]

I had a single cylinder briggs ohv that ran fine with no noticeable smoke but kept consuming oil. Due to reputation I pulled the head and found bad head gasket.

Yep, if I cannot figure out what going on, it 's going to eventually require a take apart inspection. Just too much smoke to try and ignor. It's been cloudy for several days and I suspect some of them BLUE clouds were put up by this engine and my testing.
It has lots of good external parts and I have another engine to set on the mower.
I was hoping to find maybe only one head gasket leaking but not so for now. I have bore mics so as to check taper and out of round, etc, right now I'm just curious as to what is going on due to the leak down tests being so great, compression good, intake valves bushing and seals ok. I'll try the leak down with the piston at the bottom of the bore later. Just never seen oil smoke this bad on a small engine and not find a hint problem before taking one apart.

Don't want to put very many $$$'s into this engine, such as rings, and gasket set even if the cylinders are good..
Would just part it out.

[KE4AVB]

Just my two cents...I put the odds that #2 cylinder will the culprit or at least I have seen several Briggs v twins to lose #2 before #1.

Any I just got in a Kawasaki horizontal v twin that bent both push rods on #2 and the I can only barely move the exhaust. Looks like I got a couple days of work on it as it is on a JD 737 mower. Oh what it is to work on these ZTRs.

[Arkie]

Dropped the muffler off few days ago and smoke out of both exhaust pipes.
Finally got time to get back to the smoking engine and got a bad leak down test.
Pushed the mower into the shop with a cold engine. Jumped the push rods off both cylinders.
Had intentions of comparing leak down at different positions of the pistons in the cylinder, BUT
Checked both cylinders and really bad leakage all through their travel with the engine cold.

After confirming severe leakage I looked at both pistons with a bore scope and not much carbon on top of pistons. Both spark plugs confirm oil burning now that the carb is good.

Redneck fix for now:
I drained the oil and put in 20/50 castrol and added 6.4 oz of stp (about 10%) mix and not hardly any smoke now when engine gets hot. Was surprised how much the oil smoke reduced. (already had 25 gallon bulk container of 20/50 castrol that was given to me sometime back)

Engine had been eating severe dirt dust due to the breather tube hole in the carb intake not being plugged with the breather tube, no telling for how long the engine was operated like such. The air cleaner breather itself was not clogged or severely dirty.

Really strange to me why both cylinders leak down checked good previously when engine hot?????????? Maybe lots of oil on the cylinder walls before when testing warm/hot helping reduce the leak down and compression also seemed fair/good @ 135 on each??????
No leaking air detected coming into the push rod galleys hot or cold either. Indicates leaking now when cold is at the pistons.