OT Kohler 18HP Command Engine Question

I have gone thru my 18HP Kohler Command engine on my woods zero turn mower. I had a valve job done on the heads. It has good compression. Rings are good and engine does not smoke. This engine was apart when I bought the mower.
The problem I have with it now is when it's under a load it has no power like the timing is retarded, especially when I turn the deck on. It then starts to spit and sputter up the intake/carb. The cam is timed correctly. I'm wondering if I need to reverse the magneto coils around. Any suggestions?? Thanks John B.

I just thought that I might ask is your governor working and is it getting oil to stay lube. I just got done rebuilding a wisconsin (VGHD 4 cylinder) engine that the Governor did not get oiled which cause it to not run right.Here is a picture of a governor that did not get lubed and is a cause of not acceleration on the engine.

Confirm it is running on both cylinders.
I had a 20 hp Command that ran like a clock at idle, but under load it ran just like you described.
Mine had messed up rocker arms and was only running on one cylinder.

Could be ignition issue on a single cylinder too. I have a Command 20 Horizontal that had a bad coil. Ran perfectly on one cylinder, until you asked for power.

I agree check to make sure both coils are working.
Mine works in reverse.
When I turn off the switch it stumbles and coughs like he11.
Only one coil gets grounded out.
I need to pull the engine out to get to the coil.
I need to reconnect the kill switch to the coil.

I have a ZTR with either that engine of the next size up.. Bought it new and it always had similar sounding problems. Had the carburator cleaned and it runs better than it ever did new. Mechanic said not to use ethanol gas, which I wasn't doing anyway.

KEH

I recently purchased a used 18 hp kohler command horizontal shaft off a Cub Cadet. Only paid $35 for it. I purchased it because it has an old style carb with adjustments. My 20 hp command has fixed jets. A kohler coil costs $50, so I feel like I got a bargain, 2 coils, carb and starter.

That said, my 20 hp command has no timing. The magnets on flywheel are in a fixed position and the coils go in a fixed place. No timing. I use 3 one dollar bills to space coil above magnets before I tighten the coil in place.

One thing I've learned about the kohler carb is there are 3 tiny vent holes on the top part of carb. They must be kept clean or the engine will run rich. I use 30 psi of air and blow each vent hole out and you will see a stream of gas come out holes above throttle plate.

The used engine I purchased didn't had 300 hours on it. The engine was used is a dirty environment on the Cub cadet. The owner said the engine overheated and he junked it out. WOW, over heated and 100% blockage in head cooling fines. Go figure a Kohler earns a bad reputation for not lasting 300 hours when the IDIOT didn't take care of it. I have 1500+ hours on my Kohler, use no oil, never had heads taken off, done anything except preventive maintance.

If any engine doesn't get enough gas, it won't make power, just that simple. However if it gets too much gas it won't work right either. Look at spark plugs, if black with carbon, too much gas. My experience is that a lean engine will run just fine until it's put under load. It takes gas to feed the all horses. Check air filter, gas filter and you may have to take carb apart to check for any blockages. You may have too low of float level or the governor is set to respond too fast, carb can't keep up. Good luck.
George

Thanks for all the info. I do know that one coil faces one way and the other is facing the other by what the service manual says. It does run on both cylinders. I'll do some more checking this week and let everyone know what I find.