CV740 27hp bogs severely under average load

An IR temp camera will show you exactly what is going on. Twin cylinder running issue? Will show you which cylinder is running proper or not. Dragging starter? Will show you immediately where your battery cables and such are heating up excessively. T-Bone over on Raley's Small Engines made a good video on this pertaining to mowers.

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Turbodriven said:
I did this and just grounded the unplugged boot with a alligator clip test lead. (note, I think these new MDI coils have built in protection though. As they have a lead running back from the boot and grounding out under a bolt of your choosing).

Neither side runs great by itself and neither would hold idle. The only noticeable difference between both sides is that when #1 was running, I was getting black sooty exhaust (noticeable). Whereas the #2 did not. I suppose this is to be expected. Edit: I realize though, that with black soot coming out of #1 under a no-load situation, it confirms that this is indeed a motor problem and not a loaded hydro (or other external) issue.
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You don't lose just 50% power on the loss of a cylinder....more like 75% with pumping losses and additional frictional losses....and that depends on whether the compression isn't degraded from hours use. Plus it's turning those two hydraulic pumps when moving and stationary but the load only appears when doing actual work to move the hydraulic motor.
 
Wish these forums had a search function.....anyone ever confirm that the coils were actually putting out proper spark? And that the coils were mounted in the correct location? Kawasaki twins have a left and a right coil that are different and separate from one another....can't vouch for the Kohler that powers this machine.
 
ArCanSawDave said:
Zombie thread, but I figure I'll add just in case someone else has a similar problem. I'm dealing with the same problem on an old Woods 5182 61" deck with a Kohler CH18. In my case the engine runs fine no load but as soon as the blades are engaged the RPM drops significantly. What I'm finding is that one of my coils is losing spark only under load.
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Yup. These coils tend to age over the years as this is a lost spark system that fires every revolution, not just when that particular cylinder calls for spark. Multiply 3400 x 60 x the number of hours on the engine......that's a number in the millions. These are also...sometimes....electronically switched coils. Heat over many years will degrade the transistor and cause a slow fade in spark intensity.
 
RevB said:
Yup. These coils tend to age over the years as this is a lost spark system that fires every revolution, not just when that particular cylinder calls for spark. Multiply 3400 x 60 x the number of hours on the engine......that's a number in the millions. These are also...sometimes....electronically switched coils. Heat over many years will degrade the transistor and cause a slow fade in spark intensity.
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Interestingly enough, I just replaced both coils at the end of last mowing season. I looked at everything except the coil because "There's no way a brand new coil is bad right!?". I've installed a cheap inductive tach to keep an eye on the RPMs, these engines run surprisingly smooth on one cylinder. It was a real hassle getting the correct coil because the Kohler engine identification sticker is missing from the blower housing. I ordered Kohler P/N:24 584 201-S. There's apparently quite a few different ignition systems on these engines.
 
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