Kohler CH740 power issues.

[F150Fan80]

You use your ears. If the air from the cylinder is coming out of the air filter housing then you have a leaking intake valve, not to be confused with air that could be coming out of the breather tube connected to the air filter housing from the engine block, but this can be prevented by removing the dipstick. . If air coming out of muffler then exhaust valve leaking. If air is rushing out of the dipstick tube then that would be worn/damaged rings or blown head gasket. Some air coming out of the dipstick tube is normal since there will be air bypassing the rings to some extent. Also air leaking past the valve can mask worn rings or head gaskets issues.

You will need to pull the head in the end but it will give you some direction to what to look for.

So I got to the leak down test. Warmed up the engine for about ten minutes. I ended up taking the valve covers off to help find TDC on compression. Good news is that it seems like the valves are sealing decently. Bad news is it appears that the rings are worn. Looking at a complete rebuild at this point from what I gathered. Also noticed some white stuff under the valve covers. The plugs looked weird to me. The oily one came from the side with the better compression. The other plug came from the side with the lest compression.

 

[Fish]

So neither side will start it?

 

[Fish]

white substance usually means water in the oil.

 

[bertsmobile1]

As fish mentioned the milky colour is water and common to find it in rocker boxes where water can condense overnight depending upon the local weather conditions, nothing much to worry about unless all of the oil is milky.
If you do not run the mower for long enough to boil it off it can persist for a very long time.
The plugs both look lean
The left photo just looks too lean and probably the wrong grade of plug.
The right is hard to tell weather the plug is damaged or it is just a bad photo
If I am seeing little chunks taken out of the plug that usually means there is something rattleing around inside the head.
It is what a plug looks like when one of the butterfly screws falls out and gets sucked into a cylinder

 

[F150Fan80]

So neither side will start it?

It tried to start on both but I didn't let it go for too long. One side seemed stronger though while trying.

 

[F150Fan80]

As fish mentioned the milky colour is water and common to find it in rocker boxes where water can condense overnight depending upon the local weather conditions, nothing much to worry about unless all of the oil is milky.
If you do not run the mower for long enough to boil it off it can persist for a very long time.
The plugs both look lean
The left photo just looks too lean and probably the wrong grade of plug.
The right is hard to tell weather the plug is damaged or it is just a bad photo
If I am seeing little chunks taken out of the plug that usually means there is something rattleing around inside the head.
It is what a plug looks like when one of the butterfly screws falls out and gets sucked into a cylinder

No screws have fallen off the carburetor. I have had it off a couple of times in the last two weeks and they are all there. As far as the lean condition I would have to agree. I have never adjusted this on the carburetor since owning the machine. The adjustment is behind an aluminum plug that just recently came off when I installed a rebuild kit. The needle was placed back in the exact same spot where it was. Both plugs are Champion RC12YC, which is what it called for in this. Here is another picture of that other plug. This should be a better view.

 

[ILENGINE]

Looks like possible gas additive deposits on the electrode. Threads on plug look like plug not properly tightened down allowing compression to seep past the threads.

 

[F150Fan80]

Looks like possible gas additive deposits on the electrode. Threads on plug look like plug not properly tightened down allowing compression to seep past the threads.

Never thought of that. It was snug in the hole but not as tight as I would have thought. Maybe it wasn't sealing. That side had the best compression during the test. I have the oil draining currently. Once it's done draining the engine is ready to be lifted out and on to the bench. I did happen to notice the wiring harness connector has seen better days. Here are some pictures of that.

 

[F150Fan80]

So I recently started working midnights and haven't had much time with the engine. I did get lift it out of the mower (by hand :frown and set it up on the bench. I started tearing it down by removing all the shrouding, plates, muffler, throttle control, etc. It's finally ready for me to pull the heads hopefully this afternoon after I wake up before work. I had started to look around for possible rebuild kits. I have found one site that offers them but not sure if other places do. There were quite a few different options. Not sure what the best one would be but then again I haven't gotten into the engine to see how things look. I will leave the link for the website I found and see what you all think. Should I lap the valves while in there? I'm assuming yes but wanted to what the consensus is. Here are a couple pics of the progress. Also, what do you think about the wiring harness connector here? Looks rough. One terminal looks as though it got pretty hot. Not sure what happened to the plastic. Should it be replaced? Can it be replaced?




http://www.psep.biz/store/kohler_rebuild_kits.htm

 

[Fish]

Looks like your engine has smartspark, I looked up your engine and it said that you did not, so I didn't suggest it.

That is very likely your problem