Spark plug firing order

[John Kieffer]

2012 work horse with 11hp Robins 2 cylinder 4 stroke engine. I’m trying to rebuild an old discarded work horse. I have a simple question. Does the twin output coil fire both spark plugs at the same time or does it alternate between the plugs? I haven’t got mine to fire at all yet, but I will!

[kgsc]

Both at the same time. No distributor

[CP241]

2012 should have the Kawasaki single cylinder motor in it. 2008 I believe was the last year of the 2 cyl Robin's based engine.

[John Kieffer]

Thanks for the quick response. I could not figure anyway that the coil could know which one to fire, yet it seemed odd to think that both cylinders would be firing at the same time. Seems like the engine would run much smoother if they alternated. This is my first experience with one of these engines. I must have the year wrong. Maybe it’s a 2002. The previous owner said it had wiring problems that they couldn’t figure out. It got replaced and sat in the woods for years. This combination starter/generator is an interesting concept. I still haven’t got my head around how it knows how to exit the starter mode and go to generator mode.

[CP241]

It's a wasted spark setup. The pistons alternate compression strokes, but plugs fire both compression. And exhaust strokes. Not an uncommon setup for an engine. They run very very smooth once you get it running.

Once the starter/generator begins to spin faster than it can spin on its own it becomes a generator. Dont know exactly RPM off the top of my head.

The ignitor is mounted to a vertical plate next to the battery. It gets ground through this plate and is very common for it to get corrosion between the plate and the body. I'd start by removing it, wire brush the bottom of the plate and the body, and run an extra ground wire directly from one of the bolts on the mounting plate to the negative battery terminal. I've fixed a few with a no spark issue this way.

[meimk]

Originally Posted by John Kieffer

I could not figure anyway that the coil could know which one to fire, yet it seemed odd to think that both cylinders would be firing at the same time. Seems like the engine would run much smoother if they alternated.

Golf carts are a bit different from the automotive stuff most of us have been used to, but the "Wasted Spark" ignition was pretty common in cars through the 80's, 90's & early 2000's. In practice the spark happens at the top of the compression stroke for one cylinder and the top of the exhaust stroke for the other - so it's simple and really doesn't hurt anything to "waste" that spark.

[kgsc]

It also supposably burns excess fuel not burned from the power stroke.