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Kohler CV740 ignition coil position at TDC?

#1

Turbodriven

Turbodriven

Without pulling my flywheel to check the key, can someone tell me if this timing looks right? Pictures are of both cylinders at TDC.

Motor bogs down under load. Motor has 170-175 compression. Fuel system is new front to back. Both cylinders are getting spark and pass all the Kohler manual ohm and timing light tests for "smart-spark" coils. The only anomoly is that Cyl1 plug is dark carbon black and Cyl2 is golden brown/white after running 5min with new plugs. Running out of options to check here. :(

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#2

V

VegetiveSteam

The ignition is timed to fire before TDC so the magnet being past the ignition module with that side's piston at TDC is normal. How much past is too much? That's a good question. Since the flywheel key needs to only be partially sheared to cause an issue there's really no way to tell by looking. That being said a sheared flywheel key on a Kohler twin is not unheard of but isn't very common if that helps.

If it were an ignition timing issue it would probably affect both sides the same. Maybe clean the spark plugs and swap the modules from side to side and see if a dark spark plug develops on #2.


#3

H

hlw49

Check the valves for lift could have a worn cam.


#4

Turbodriven

Turbodriven

hlw49 said:
Check the valves for lift could have a worn cam.
Click to expand...
Can you outline this procedure?

I had both valve covers off earlier today and measured as best I could both sides (cyl1 & cyl2) as I rotated the crank. All the valves had very close to the same travel. Nothing seemed out of the ordinary.


#5

Turbodriven

Turbodriven

VegetiveSteam said:
The ignition is timed to fire before TDC so the magnet being past the ignition module with that side's piston at TDC is normal. How much past is too much? That's a good question. Since the flywheel key needs to only be partially sheared to cause an issue there's really no way to tell by looking. That being said a sheared flywheel key on a Kohler twin is not unheard of but isn't very common if that helps.

If it were an ignition timing issue it would probably affect both sides the same. Maybe clean the spark plugs and swap the modules from side to side and see if a dark spark plug develops on #2.
Click to expand...
I pulled the flywheel bolt off and looked in the keyway with a flashlight. It appears to have a key, and it looks lined up and intact.

I think I will swap ignition modules like you suggested and see what that does to my plugs. They both ohm tested good and are putting out (what appears to be) normal spark under no load in the garage. But maybe when I'm out in the yard under load the #1 becomes weak? Swapping will confirm it's not an ignition module (coil) issue.


#6

V

VegetiveSteam

Turbodriven said:
I pulled the flywheel bolt off and looked in the keyway with a flashlight. It appears to have a key, and it looks lined up and intact.

I think I will swap ignition modules like you suggested and see what that does to my plugs. They both ohm tested good and are putting out (what appears to be) normal spark under no load in the garage. But maybe when I'm out in the yard under load the #1 becomes weak? Swapping will confirm it's not an ignition module (coil) issue.
Click to expand...
Swapping them is a fairly easy way to possibly rule out the one module. If the dark plug stays on #1 it's probably not the module. Was old #1 spark plug also getting black like the new one?

And unfortunately since Kohler uses a half moon flywheel key, simply taking the bolt out and looking at the key doesn't really tell you anything. You have to remove the flywheel to know for sure. Chances are the key is good but there is only one way to know for sure.


#7

Turbodriven

Turbodriven

VegetiveSteam said:
Swapping them is a fairly easy way to possibly rule out the one module. If the dark plug stays on #1 it's probably not the module. Was old #1 spark plug also getting black like the new one?

And unfortunately since Kohler uses a half moon flywheel key, simply taking the bolt out and looking at the key doesn't really tell you anything. You have to remove the flywheel to know for sure. Chances are the key is good but there is only one way to know for sure.
Click to expand...
Yeah, when I first brought the mower home (bought cheap, with issues), one of the first things I did was pull both plugs and the #1 was dark dry black and the #2 was golden brown. I've swapped clean plugs twice since and #1 always comes out dark dry black while the #2 varies from white to golden brown.

I'll pull the flywheel, just to be 100% sure the key is in place, then swap the coils (they come off anyways with the flywheel). At a minimum that will absolutely rule out the coils and the timing being issues.


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