Small Engines (Lawn Mowers, etc.): john deer 285, twin cylinder engines, aligater

Question
Hello Dave. The cylender on the right side is firing and the mower will run. The coil on the left side has voltage going to it but puts out no spark at the end of the plug and the cyl is just along for the ride. I have replaced the plugs. Since both coils are idenical I reversed the coils but the mower would not start and there was no sparl from either side when I did this. I put the original right side coil back in place and the mower runs again. I unhooked the 2 wires from the right side coil that will work and with 2 aligater clips ran from the right side to the left side and also put the coil from the right side on the left side. The mower would not start and sounded like it was out of time at this point. Do you have any idea?

Answer
Yes...I have an idea.... AND your not gonna like it....IT sounds like you have a broken connecting rod on the cylinder that wont run.  This is common on twin cylinder engines.

The typical symptom is the engine will start and run fine, until you engage the blades, as soon as blades are engaged engine runs terribly.  

Take a compression tester and take a cylinder reading on both cylinders.  If one has 0 psi, I am afraid you you are looking at a very costly repair bill.

I do hope im wrong... do this test and get back to me... there are also diodes in the wiring harness that MAY be causing this, but im not confident this is the problem.