Re: The engine ran great!!!….except when it didn’t.

[nj-boatbuilder57]

Well, folks, here’s the deal. I am completely, totally, 100% UN-able to make this engine run badly.

I’ve bucket run this thing for the last few weeks. I’ve spritzed the wiring with a spray bottle full of water while running, trying to get the ignition to arc out. I’ve run it in the dark to look for arcing. I’ve pulled the flywheel & inspected everything. Looked for arc spots and/or carbon spots. Replaced the caps, too. I’ve disconnected & reconnected the mag kill wires. All of the wiring is 100% new, but I’ve re-traced everything anyway looking for anything suspicious. I’ve removed & re-seated the spark plug wires/boots too many times to count. This engine starts easily & promptly, and runs well.

Measured the spark energy with a tester: constant & strong, averaging around 37kV.

I suppose I shouldn’t complain about a well-running engine, but there’s no denying that twice (on an otherwise perfect 2-week vacation of daily use), there was an ignition issue with what I suspect was one cylinder not firing. Hard starting, rough running, lots of un-burned gas in the exhaust. It happened……yes, it did. But it wont now.

Frankly, the ignition system of a 2-cycle magneto-based engine is a pretty simple device. There’s just not that much to go wrong…and I’ve done everything I can think of to tease out a problem.

Thoughts?