Small Engines (Lawn Mowers, etc.): Kohler M20 leak spark, blue spark, timing light

Question
QUESTION: The Kohler M20 started running rough when hot last year, so this winter i installed a new coil. Ran great for a couple minutes and died. Tried to refire and nothing. Checked the coil with a timing light and the rightside cylinder had good fire and the left had leak fire. Tried starting with ether and it acted like a timing problem because it blew all the ether out the exhaust. Removed the flywheel to check the flywheel key and it was good. Checked compression and it was good, and checked for fuel and had good fuel. Please help.

ANSWER: What was the compression in each cylinder? Also I am not familiar with the term "leak spark"...What do you mean by this? Have you tried checking the gap on the plugs, and or replaced them recently? Sounds as if the fuel is not being ignited in the left cylinder. Check the spark with the spark plug grounded to the block outside the cylinder and with the boot connected. Make sure it is gaped correctly. Is it producing a bright blue spark? When running using spark plug insulated pliers, and removing the left plug wire is there a noticeable difference in how it runs, this will tell you if the cylinder is firing too.....Tom

---------- FOLLOW-UP ----------

QUESTION: I think the compression was 120 give or take. I meant weak spark. I have replaced the plugs when i replaced the coil. What I am wanting to know is what would cause the spark to be weak on the left side and not on the right. The magnet on the flywheel picks up on the outsides of the coil or does it pick up on the inside point of the coil. Im going to put the engine back on the tractor and see if adjusting the coil helped.

Answer
120 psi isn't that great actually, the last Kohler I did last week had a lot of hours on it and was pushing 155+....The big question is are both cylinders at the same compression?...I have to admit I haven't seen one cylinder with a weak spark and not the other. testing a spark with a timing light isn't the most reliable way, the best way is with a spark tester, then you know if it is able to jump the right gap. Did you try pulling the plug wire with it running to cancel out the left cylinder and notice changes?........Tom