One cylinder, two spark plugs?

[titaniumneck]

First off I really want to thank everyone here on being so cool with me. I am a new member and have received positive feed back.
Now for yet another question, my Tohatsu 2 cylinder has both spark plugs going to one coil. How's that work? I am asking because I am getting a motorcycle tachometer that wraps up wire around one plug wire. So how does one coil run two plugs?

 

[bruceb58]

It's a wasted spark system.

 

[Sea Rider]

It's a siamese coil, both plugs fires at same time per 1 full revolution, wrap cable on any plug cable, is it fire sequence programmable or non programmable induction tach, is it a Hardline tach ?

We aware that if you see low or high readings on window display, that tach is no good for that OB if being a non programmable tach. If programmable adjust to 2 sparks per revolution to read correct rpm.

Happy Boating

 

[wrench 3]

Assuming that you have a 4 stroke engine, it will fire twice per 4 stroke cycle. Which adds up to 1 spark per revolution.

 

[fhhuber]

Common way to set up a 2 cyl ignition on the cheap... 2-stroke or 4-stroke. I've seen it on both. 2 stroke would just have 2 magnets 180 deg from each other on the flywheel to actuate the magneto.

Lots of 2 cyl 2 stroke jet skis by Kawasaki have this system,

 

[titaniumneck]

It's a two stroke, and I haven't received the tachometer in the mail yet. But it is programmable. I kinda thought that about both plugs fireing together. Just wanted to make sure, so thanks for confirming it. I bet they charge as much for that one coil, as if were two.

 

[Sea Rider]

Common way to set up a 2 cyl ignition on the cheap... 2-stroke or 4-stroke. I've seen it on both. 2 stroke would just have 2 magnets 180 deg from each other on the flywheel to actuate the magneto.

You're completely out of date with respect to Tohatsu OB's. RPM is measured at any of both exiting IC cables. Just 4 wraps on middle or near plug boot, tie, cut cable excess, with engine ON and set to RPM, re program firing sequence scrolling down with button till (2P) is displayed and voil?..

Happy Boating