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I know what I don't know, which is very much about electrical issues... 510h on KT17 engine which was running well after quite a bit of TLC (new: fuel pump, fuel lines, fuel filter, spark plugs, ignition leads, coil, air filter, battery, battery cables, new points but not condenser; cleaned/lubed starter, cleaned carb, cleaned fuel tank; replaced both intake valve retainers). I can't get it to start/run. The cyl compression is 60psi after 3 cycles on the left (as you're sitting on tractor) and barely 20psi after 3 on the right. Valves on RHS appear to be moving appropriately when engined cycled. Also, I have a consistent spark (ign lead with spark plug grounded to exhaust shield nut/stud on the lower coil HT post (for short ign lead to Left cyl) and poor rare spark to RHS (long wire). I'd played the permutation game by moving a 'working' lead and plug (with obvious visible spark) from lower to upper HT post and had the same issue, so it's not the ign leads or plugs.

Here's how simple minded I am: I ordered up a new coil (again) and it behaves exactly as the existing new one. They test out the same as well (continuity across the LT posts, same resistance across the LT and then HT posts).

Here's the question: how can I have a consistent spark on one side (left) and a rare intermittent one on the right?
 

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If the coil produces the spark OK and checks out, then the HV ignition leads carry that voltage to the plugs, where the energy is released in the form of a spark. So, there are only three (3) parts involved. Coil, leads and plugs. Something is causing a diminished spark.

BTW, I have had brand new spark plugs out of the box be bad.

Click on this link for a simplified KT-17 Ignition Circuit..... Circuit

According to the Kohler Service Manual, there should be no greater compression difference between cylinders, than 10%. In addition, the lowest acceptable compression value, is 50 PSI.
 

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HI paddythesmith,

Did you check the compression before you did the retainers? According to the info that RBedek supplied you have a sealing issue with the right cylinder. You might want to recheck the valves on that side and if not the valves then you probably have bad rings or valves seats.
 
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