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Small Air Cooled Gasoline Engines

Kohler Magnum 18 twin backfire


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  #1  
Old 01-25-2019, 06:16:23 PM
miraclewhip miraclewhip is offline
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Default Kohler Magnum 18 twin backfire

Engine ran strong without problems for years,then was running only on 1 cylinder.I removed head from non-firing cylinder and verified valve operation and no carbon buildup.replaced head and backfiring occurs. Engine will not start with 1 sparkplug removed ,or with both installed.Replaced plugs with new,and tried with old. No difference! Any ideas?
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Old 01-26-2019, 11:30:40 AM
Tom Schaech Tom Schaech is offline
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Default Re: Kohler Magnum 18 twin backfire

Several things need to be assessed here to determine the source of the problem. Do you have (or had) spark at both plugs? Did you perform a compression test on each cylinder to determine the PSI on the cylinders? Check ground wires for continuity? Is it backfiring when shutting off? These have anti-fire solenoids on the fuel bowls that have been a perennial problem-to the point where Kohler says to shut the engine off at full throttle. One coil or two? I've seen them go bad, especially if the cooling fins get clogged up and overheat the coil.


Tom
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Old 01-26-2019, 07:16:44 PM
miraclewhip miraclewhip is offline
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Default Re: Kohler Magnum 18 twin backfire

Tom,thanks for your checklist of suggestions. I opened both Valve covers and found the valve spring guide on one intake valve broken and valve retainer lying in valve chamber! Next I will check to see why the breakage occurred.
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Old 01-28-2019, 04:10:05 PM
Tom Schaech Tom Schaech is offline
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Default Re: Kohler Magnum 18 twin backfire

I think you've located your problem. Keep us posted!!!!
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