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Old 05-31-2018, 10:24 AM   #12
Nomad Willy
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City: Concrete Washington State
Vessel Name: Willy
Vessel Model: Willard Nomad 30'
Join Date: Oct 2007
Posts: 18,743
That’s easy,
Two stroke.

But I don’t think they developed four stroke outboards for emissions. The first 4s I remember was an OB called Lawson. Four hp as I recall but there may have been others.

The first large 4s OB was the 55hp Homelite. And I think it was to appeal to folks that were alergec to smoke and mixing. And of course everybody likes the much smoother idle. But smoother above idle is a tossup IMO. And then there’s noise. At an idle the 4s is king as it is w smooth running. But who runs a marine engine at an idle? Most all get worked hard and while working a 2s is king at mid throttle (the usual) as twice as many power strokes is an advantage. A small 2s OB at mid-low power is sweet indeed.

But since emissions came along the big difference is weight.
The heaviest thing in an engine is the crankshaft. Many car engines suffer a bit from excessively light crankshafts and I’ll bet 4s OB’s do to.
Motorcycle Grand Prix racing saw only one 4s contender for many decades (Honda) and weight I’m sure an issue but I think it was more a matter of power. Nothing could match a screaming two stroke. Honda was determined to win though and went to extreme measures. One I recall was elliptical cylinders. One can easily imagine some really big valves. Can you imagine building it? But none of it ever produced a win for Honda.

The combination of a sweet mid-range and light weight makes the 2s irresistible to me. But I have one 4s .. 60hp. I bought it new and mostly for less fuel consumption. But for small OB’s it’s 2s all the way for me.
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North Western Washington State USA
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