Kohler CH740 power issues.

[F150Fan80]

Doing a compression check could confirm if you still have a low compression issue. I am wondering about the remove muffler and it ran better. You could have a restriction in the muffler that would cause power related problems. I have seen the baffles come loose in mufflers and restrict the outflow,

I can try doing another compression test and seeing what it shows. If it shows low then a leak down test would be next. If I was losing compression again I would bet the valves aren't sealing properly since it's been honed and new pistons and rings. I'll know more later this week. It seemed to engage much easier and bog down what I would consider to be normal during the initial PTO engagement at a lower RPM. The muffler doesn't rattle or anything so I am not sure if something did move or not. I'll try to get to a compression check tomorrow night after work.

 

[F150Fan80]

Leak down test would be better valve sealing problem.

I do have question since it seem taxed with the PTO on. Are you sure it is running on both cylinders?

I'll start with the compression check and go from there. I have a leak down kit as well if the test shows low. My bet would be a leaking valve, possibly not seating correctly. I'll hopefully be able to run a compression check tomorrow after work. It does seem to be running on both cylinders.

 

[F150Fan80]

So it appears that I still have low compression although not near as low as it was. One cylinder was at 130 and the other is at 140. Note that this is found on a cold engine. I have yet to perform a leak down test but I am relatively sure that it is leaking through the valves since I have brand new rings and pistons, along with honing the cylinders. I could be wrong though. I'm guessing that the lap job I did on the valves was insufficient. I may just look for someone local to go over the heads and make sure everything is seating and sealing properly. Anyone else have any ideas? It's almost discouraging after going through all that work and here is where I ended up. ?‍

 

[AVB]

Without going back and reading the whole thread it possible that honing isn't complete. Even if you just break the glaze you should use a rigid hone in the cylinder(s) are oval or tapered. All a flex hone does is to break glaze or hone in the shape as it was before you try honing. Just a thought...though.

 

[F150Fan80]

Without going back and reading the whole thread it possible that honing isn't complete. Even if you just break the glaze you should use a rigid hone in the cylinder(s) are oval or tapered. All a flex hone does is to break glaze or hone in the shape as it was before you try honing. Just a thought...though.

I used a three-legged hone with the spring action on the arms to hone them out. It's done well for me in the past but maybe not in this case.

 

[Scrubcadet10]

How much run time On The rebuild? Rings may not be sealed well yet.

 

[F150Fan80]

How much run time On The rebuild? Rings may not be sealed well yet.

Not a whole lot at all. Basically I've ran it for about 20 minutes give or take. Probably a little more. I figured It would be a little better now. It seems like the issue I was having in the beginning is still present, even with the low compression that was originally found. Perplexing issue and annoying to say the least after all this.

 

[F150Fan80]

So I was finally able to test the muffler of sorts by stuffing a rag in one inlet and then inserting a rag and compressed air nozzle into the other to see how much air was actually leaving the muffler. I also reversed the inlets and tried again. It really didn't seem like there was much of a restriction. The air the came out was not traveling as fast compared to what was coming in, due to the large pressure drop, but seemed adequate. There was really no difference in the sound or amount of air leaving the muffler from either inlet. There was no rattling either. If the muffler is indeed "clogging" could it be cleaned with solvent or should I just buy another? ILENGINE, I would love to hear from you on this to see what you think. Obviously I am open to all thoughts as well. This is turning into a nightmare trying to get it to run well again.

 

[ILENGINE]

I kind of wish I could hear this thing run with and without the deck engaged. It could be a fuel issue related to the high speed jet side of the carb, either slight restriction in the jet causing slight lean condition. Even though the compression is slightly low I don't think it would be real noticeable unless you were really lugging the engine in tall grass.

I will keep thinking maybe I will come up with something else.

 

[F150Fan80]

I kind of wish I could hear this thing run with and without the deck engaged. It could be a fuel issue related to the high speed jet side of the carb, either slight restriction in the jet causing slight lean condition. Even though the compression is slightly low I don't think it would be real noticeable unless you were really lugging the engine in tall grass.

I will keep thinking maybe I will come up with something else.

I am ok with going through the carb again. I did a rebuild kit on it as well. This was before I found the compression issue. It still persisted. I am always game for trying to clean it again.