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Hey guys I'm new on the site and have a question I've been working on an 18hp kohler magnum engine. I got it running but seem to have an issue with it . My problem is one cylinder seems to fire better than the other. Compression is good on both cylinders, intake is clear on both sides but it seems to run hotter on one side as compaired to the other. Is this common or do I have another issue?
 

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maybe an intake leak on one side, or a valve is sticking, or maybe spark plug/ignition isn't quite right on one side?
 

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Is the carburetor a single or two barrel setup? A single would feed the same mix to both sides, while a twin could be feeding a different mixture to both. Have you checked both sides intake manifold gaskets and sealing? Sometimes a gasket can get damaged, and 'sort of' repaired by tightening the fasteners, and then, after time, develop a slight leak, allowing in too much air. That would generally cause a 'lean' condition on that side.
If you have the Kohler spark system that provides for timing advance, the SAW system, be aware it has been replaced by something else(which does not have the problems SAW seemed to have). I do not have model equipage memorized, just throwing that out as a common problem for vintage larger Kohlers.
Have you inspected the spark plug deposits? Checked for spark occurring all the time, using a timing light to watch the flicker on each plug wire? You might want to check valve clearance as not all Kohlers have hydraulic valve adjustment. I do not own one, but some of the twins have mechanical valve adjustment. If clearance is too small, a valve can be held just shy of seating properly, leading to leakage, misfire, and valve damage(over time). A valve that is not seated cannot transfer heat from the valve face to the valve seat, and will overheat and fail. A bad valve spring can cause similar conditions, as can a weak or broken valve spring.
tom
 
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