Kohler CV20S-65540, Valve Problem, cylinder overheating Scag

So at work I had a project put on me. It was to clean up someone's mess. We have a scag mower that originally came with at CV22S. This guy put a used CV20S in it and the #2 cylinder overheated and the valve seat fell out. When I first started my job (over 2 years ago) I saw the mower and engine in pieces. The other guy managed to order a new head. Well It finally became somewhat a priority to get it going so I had to clean up this guy's mess and put something back together that i didn't take apart (which I HATE). I had the brand new head, ordered valves, seals, gaskets and whatnot. I installed everything, with a new fuel filter, brand new gas, new plugs, Cleaned the carb and intake manifold, bled the hydraulic lifters to check for proper operation. I started it up finally yesterday. It sounded good, as in I think both cylinders are firing correctly, ran it for about 4 minutes, then revved it up to blade cutting speed for about 30 seconds, then put it to idle for about 30 seconds, and then shut it down. The thing I noticed is, the #1 cylinder I could hold in my hand, wasn't hot enough to take my hand off, got close though. The #2 cylinder, the one that overheated before, was on fire, couldn't get my hand near it without burning. Now that temp could be normal operating temp, because Cant normally touch an engine after running. But the thing that concerns me is that there was that much of a difference in temperature and that was the same cylinder that overheated and dropped a valve seat. This is my first time building and installing a head, and I followed all the instructions verbatim.

I don't want it to blow up again, so is there anything I can do to see if there is a problem? Like I said I only ran the engine for 5 minutes. I have access to some equipment, but not sure what to do to see if something is wrong. I have a compression tester, Leakdown tester, and IR thermometer.

Another thing, I think I have to order a choke lever for the carb, No mater what way I put it on, it doesn't seam to operate correctly and looks slightly different in the drawings. It was in my parts bag when given the project, but don't know if it was jerry rigged to work or not, at 6 bucks, i'm going to order one and hopefully its different. I can assure the choke was not engaged while running, it's easy to move by hand, and it sticks well in whatever position you put it.


Notes
Scaq: STHM-22CV
Current engine: Kohler CV20S-65540
New Plugs, brand new #2 head and components
New intake and exhaust gaskets, all surfaces scotched to shiny smooth condition

First start by using new plugs or swapping the plugs.
Start by removing the blower housing and removing the wire that connects the two coils together.
Run the engine for around 5 minutes then check the heat of each cylinder.
If they are now the same, replace the wire, it has a diode in it to prevent them interfearing with each other.

Kohler have all there repair manuals on line as a free download.
Log in as a guest then go to support / manuals and dial in your numbers.

Thanks, I'll try that on Monday or Tuesday. I don't even know if I have those wires correctly hooked up, I think each coil has 3 tabs on it and have no idea what they are, the wire going into the #1 cylinder is directly coupled to the one going into the #2 coil, in the drawings its 2 separate wires I think, but I'll pull the wire off the #2 coil and try that out.

Thank you thank yo thank you!!!!!!!!!!!!!


So that was the problem. I pulled the wire connecting them and both cylinders ran. It looks like according to the manual, both wires go to the single lead side of the coil. I drove it back to the shop, turned the key off, and then pulled the plug on the #2 to kill it and it stopped fine. I thought I saw a part number in the service manual, but don't see it, It goes directly into a small harness, and by the looks of it, this has already been replaced once. Well hopefully I can find a number, or a schematic to make a new one.b

I might have messed it up though now, I was touching the wire to different prongs on the coil to see if it would work, no none of the cylinders shut down with the key Well hopefully if i need coils I can pull them off my blown CH26

If those coils have 3 tabs on them for small wires to connect, any you only have 1 wire then I think you have the wrong ones.
The 3 wire coils are for mowers with an electronic advance module ( Called SAM on Kohlers ).
If you don't have an engine repair manual, get one they are a free download from Kohler.
Electricity can not be made to go quicker on a mower so the "advance" mechanism is actually a "less retard" system.
The wrong coils will therefore be firing at the wrong time so will tend to overheat the engine.
The mechanism for this is rising voltage generated in the coils and because bot coils are on a common kill wire, rising voltage in one can interfear with the other which is why the diode got put in there.

I can never fathom the full Kohler engine spec numbers but somewhere in there is the coding for they type of ignition system used which is why we are always pushing people to post the entire engine number not just family & Hp which are fairly well meaningless to service technicians.

Thank You again. I was reading about both ignitions last night pg 184ish or 11.13. I don't think I have the spark advanced on mine, there is no module, as well as no location where one was mounted. It says for the standard it uses the 3 prong coils, one is just upside down. and for the standard ignition it says to use the single tab on both coils. I made a new wire because the old one had melted insulation and look like it was soldered. I also found that the pin in the back of the harness where the kill plugs into, slipped out a little. Everything seams good. Starts nice and easy and shuts off with the key now. Ran it for a little bit, both cylinders were at about 270ish. Then cut grass all day the next day and ran perfectly.

Thanks again for the help.

Traditionally the CV20 was not a spark advance engine. That was only used on the CV22 and larger. The 18,20, 22 all use the same block the 18 has a throttle butterfly stop screw, the 20 didn't, and the 22 had the spark advance modules. Sounds like somebody put the 22 advance modules on the 20 and didn't change the flywheel if there is a different flywheel for that engine.