2 Stroke vs 4 Stroke Outboard motor mounts

[a64pilot]

Most likely two stroke outboards are a dead product line, I’m sure Yamaha sells them as they make a killing doing so, they sell at about the same price as a four stroke but are much cheaper to manufacture, the tooling is all there so they will keep making them as long as they still sell, but I doubt there is any research and development going on, I bet there has been little change for years.

Remember the old Kawasaki 750 triple? 12 sec 1/4 mile and 120 mph top speed and 74 HP, a real monster. Known as an H2, First time I went faster than 100 mph on a motorcycle.
https://en.wikipedia.org/wiki/Kawasaki_H2_Mach_IV

Well there is a new H2, this one is a four stroke and makes a bit more power, it’s also 1000cc
https://en.wikipedia.org/wiki/Kawasaki_Ninja_H2

[s/v Jedi]

I agree with a64, the new 4-strokes are winners and will kill the 2-strokes.

My 2-stroke Enduro 25 was 120lbs and the new 4-stroke Mercury 20hp with electric start is 99lbs. Without electric start it would have been lighter per hp.

The new outboard feels just as fast as the old one but makes much less noise, uses half the amount of fuel, much easier to pull-start and much better for the environment

[wingssail]

OK you guys, you seem to be piling on for no reason.

I agree that 4 stroke outboard motors are the future, for environmental reasons if nothing else (yet).

But it is a little rich for you to be inventing arguments which are not true to justify your position.

Originally Posted by MicHughV

whoa.....I thought the whole move to 4 stroke outboards was to eliminate the gas/oil mixture required of 2 strokes...yes/no ??
No, the only reason that they changed was because the US government outlawed 2 strokes (rightfully) for environmental reasons. The reason is that much of the fuel is unburned and passed through to the exhaust, and into the environment. That is not to say that the gov't was wrong. We all can see the pollution of 2-strokes, and, of course the 4 strokes are quieter and more fuel efficient. Yes, there is no development going on for 2-stokes, while 4 strokes are advancing. We can expect them to get better, but in some ways they are not there yet.

This is (was) particularly true of the earlier version 4 strokes as manufacturers basically took the existing architecture of their 2 stroke models and added the valve train components required for a 4 stroke.

No, The 4 stroke motors were all new from the crankcase to the valve trains, including the blocks, heads, exhaust passages, intakes, everything. All of these items are totally different. Even the lower units are different. Of course the electronics are different. But the manufacturers are working to make the motors better, and they have improved, just as, for example, automobile engines have improved. The 2-stokes are dead ends, but yes, the 4-strokes are a work in progress, and it is not finished.

Manufacturers have now fine tuned their 4 stroke engines a bit to bring them in line to the weights of the original 2 strokes.

No, it is not fine tuning, it is re engineering, such as electric fuel injection, more efficient combustion and lighter components. Notice that each new advance is a whole new motor. These are not tuning efforts, and the weights are not yet in line with the 2-stokes.

Originally Posted by a64pilot

...The only advantage a two stroke used to have was weight, and that’s a big advantage, but it’s gone,

No, the weight advantage is not gone. Comparing 15 HP motors the new 4 strokes, at 99 lbs, are 28% heavier than the earlier 2-strokes at 77lbs, (Merc 4 stroke to Merc 2 stroke). The Yamaha is even heavier.

...four strokes will continue to get lighter, but they start much easier, don’t smoke, are more reliable, can idle for hours, never foul plugs, and seem to last a long time...They also use much less fuel, the little Zuki between 3 and 5000 RPM goes into “lean burn” where it doesn’t burn much fuel at all...

Maybe that is all true, but down here at the docks there re people who are swearing at their 4-stroke motors which are unreliable.

Originally Posted by s/v Jedi

I agree with a64, the new 4-strokes are winners and will kill the 2-strokes.

No, what killed the 2-strokes was the US government, for environmental reasons. Without the US Government the adoption of 4-strokes might have come along, but it would have been much slower. In my view the advantages are not compelling.

My 2-stroke Enduro 25 was 120lbs and the new 4-stroke Mercury 20hp with electric start is 99lbs. Without electric start it would have been lighter per hp.

Wrong Jedi, the 99lbs is for the lightest version. The electric start will be heavier.

The new outboard feels just as fast as the old one
Oh, come on, feels as fast? Horse power counts. Use your GPS. it can't be as fast if it is less HP and heavier.

...but makes much less noise, uses half the amount of fuel, much easier to pull-start and much better for the environment

Yeah, If we just stick to the facts we will agree, in many ways, as you say, they better than 2-stokes. The 4-stoke motors are the future, and they are all we can get now anyhow. But to me it is not clear cut.

[Cool Hand Luke]

My vote is four stroke... no need to mix fuel and also safer for environment... or so they say

[a64pilot]

I wasn’t around back then, but I’m certain that there were some that said the new plastic boats were junk, that good boats were wood, with hemp ropes too, can’t trust that new stuff.

The disadvantage to four strokes is that they are not as easy to fix by a consumer, they are digitally controlled as most any modern device is, and when these sensors go out, there is no field repair, it’s replacement time.
But it’s a lot like TV’s of old, they were pretty easily repairable, do any of you remember tube testers and tubes for sale at grocery stores etc? Back then TV’s were very expensive and when they broke you had them repaired. Now a big difference is that modern TV’s pretty much simply don’t break, modern electronics have become very reliable.