Suzuki 65 hp twin

[amuller]

Anybody have any experience with these? The one I was looking at seems to be a 1979. Truly a “big twin!” What intrigues me about it is the ignition system. Only one coil with a double ended secondary (I presume) and one primary wire. It seems to be a “wasted spark” ignition that fires both plugs every 180 degrees. This sort of ignition is common on 4 stroke engines but the first I’ve seen on a 2 stroke.

[garry-in-michigan]

Johnson used a system like that for their alternate firing twins in the 1930s. The flywheel acted as a distributer. Half was insulated and the other half would short out the ignition wire to the cylinder that was at the bottom of the stroke so the engine would not backfire. The long bronze contacts to the flywheel hub were replaced by spring loaded carbon brushes against the flywheel in later models..

• This reply was modified 4 years, 7 months ago by garry-in-michigan.
• This reply was modified 4 years, 7 months ago by garry-in-michigan.

[amuller]

I’ve read that jet skis (“Personal Watercraft”) and snowmobile engines use this type of ignition and apparently it works without backfires, etc. Hard to believe…..

[outbdnut2]

Johnson made some models in the mid to late 1970s that were something like that, having one magneto coil with two sets of spark plug wires, and two sets of points; one set of points being on each primary coil lead to ground, so when one set of points opened initiating spark, the other set had the other primary wire grounded to complete the circuit. My 1976 35 HP Johnson has this configuration.
If one set of points goes high resistance, both cylinders die.
Dave

[amuller]

What is the purpose of the two sets of points on the Johnsons? Do both plugs fire together, so there is a spark before top center and also a spark around bottom center?

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