Author Topic: 25 HP ENG.MISS  (Read 1852 times)

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Offline MATCODUDE

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25 HP ENG.MISS
« on: November 13, 2014, 11:39:47 AM »
I have a customer that has a zero turn mower with a 25hp kohler command eng. It has a miss fire on one side only, not a dead miss but a very weak cyl. He has check compression  it is 155 on both cly, did cly leak down good on both side, replaced ign coil on weak side , checked valve lift on both side, checked flywheel keyway, cleaned carb. everything looks good and is within specs, but still has a very weak cly. any ides or thoughts would help THANK YOU


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Offline cycloneracer

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Re: 25 HP ENG.MISS
« Reply #1 on: November 13, 2014, 11:46:17 AM »
Spark plug?   

Coil gapped correctly?
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Offline Cromwell C4

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Re: 25 HP ENG.MISS
« Reply #2 on: November 13, 2014, 11:50:40 AM »
Does the engine have the old style single wire solid state coils, or the multi-wire coils with the smart spark ignition module?
Tyler Cromwell - Cromwell Racing Engines - Specializing in Briggs Vanguard and Kohler Command V-twin engines, and Honda/Clone singles from mild to wild! Built to win, Engineered to last.

-Cromwell Racing engines and parts are home to numerous national championship titles and fastest qualifying times.

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Offline MATCODUDE

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Re: 25 HP ENG.MISS
« Reply #3 on: November 13, 2014, 12:18:00 PM »
It has the old style solid state coils. Has coil gap set at 10 thousands on both coils, has replaced plugs several times. I just looked at the spark plug on the weak side and appears to be wet with oil (not fuel). Had him recheck compression on both cylinders and both were 150-155.Is it possible that the oil ring is broken, but the compression ring is still ok allowing good compression, but oil to pass thru to plug.
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Offline Cromwell C4

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Re: 25 HP ENG.MISS
« Reply #4 on: November 13, 2014, 01:09:43 PM »
Make sure the coils are installed the correct way. The old style single wire kohler coils do not have the same orientation on both sides. On one side the kill wire goes down towards the cylinder, and on the other it faces outward.

And yes it is possible to have a collapsed or broken oil ring(s) and the compression rings be fine. Or you could also have a partially blown head gasket between the lifter valley and cylinder causing the oil problem.
Tyler Cromwell - Cromwell Racing Engines - Specializing in Briggs Vanguard and Kohler Command V-twin engines, and Honda/Clone singles from mild to wild! Built to win, Engineered to last.

-Cromwell Racing engines and parts are home to numerous national championship titles and fastest qualifying times.

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Offline GRUBDIGGER

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Re: 25 HP ENG.MISS
« Reply #5 on: November 13, 2014, 02:02:25 PM »
It has the old style solid state coils. Has coil gap set at 10 thousands on both coils, has replaced plugs several times. I just looked at the spark plug on the weak side and appears to be wet with oil (not fuel). Had him recheck compression on both cylinders and both were 150-155.Is it possible that the oil ring is broken, but the compression ring is still ok allowing good compression, but oil to pass thru to plug.

COMPRESSION ON A 25 COMAND SHOULD BE 165 MIN. WHAT WAS THE WATER MANOMETER READING?
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