2 stroke or 4 stroke outboard

[sailorboy1]

Originally Posted by Scorpius

Is no one on here concerned about the environment? Two strokes are HORRIBLY polluting compared to four strokes.

Like a lot of the related discussion, that is only a concern when talking about other people.

To the OP,for the most part other that the pollution the only practical difference I feel for a cruiser between the 2 and 4 stroke is the weight.

[Kenpimentel]

No one has mentioned the difference in torque between a 2 stroke and a 4 stroke. I had a 15hp 4-stroke on my dinghy and I got up on a plane without trouble. I put a lighter weight 15hp 2-stroke on it and couldn't plane. I looked at the specs and it was because the 4-stroke develops more power at lower RPMs. It was a surprising result given the 2 stroke was lighter. I was the only person in the dinghy, the 4-stroke would easily plane with 3 of us in it. This is very dependent on your dinghy, we had a Carib which has a deep V hull on it. I'm sure a flatter dinghy would have been fine.

[rapanui 2]

Originally Posted by Woodland Hills

Look at what is popular in third world countries: Yamaha Enduro 2-stroke.....

SO for that reason DO NOT TRAVEL THIRD WORLD COUNTRIES WITH YAMAHA 2 STROKES!!! because they are so reliable and easy to fix it will be stolen !! they will not still a 4 stokes!!! same problem with 4x4 truck toyota Hilux!!!

[Bycrick]

I live full-time on the boat. I don’t have a car. Most of my electrical needs are supplied by solar. My carbon footprint, by comparison to most, is vanishingly small. But the do-gooders are going to try to tell me that I’m destroying the environment by using a 2-stroke outboard a dozen times a year. I’m supposed to sacrifice lightness and easy maintainability so that they can feel good about "saving the planet."

Nuts.

[scareygary]

Originally Posted by TrailerCruiser

Which is more dependable and easier to fix, a two-stroke or a 4 stroke? I'm looking for a 15hp short shaft outboard

I see that your handle suggests you are a trailer sailor. I don't have it any more, but sailed a Catalina 25 swing keel for many years. I used a 10 hp. four stroke Yamaha as an auxiliary. It had more power than I really needed and was very efficient. Issues with the earliest ones (from the 80s) was long since resolved, imho. My 10 hp was a 'high thrust' model that turned a huge prop and had more thrust than any 15 hp I can imagine.... I don't think the answer is in HP, but in the resultant THRUST it provides. If I'm off base, I apologize, but I'm trying to get you to think about something you might not have considered. I always used small 2 strokes for dinghies, mostly for weight savings. They never got enough use to amount to much pollution, imho...

[tdunlap]

Originally Posted by Kenpimentel

No one has mentioned the difference in torque between a 2 stroke and a 4 stroke. I had a 15hp 4-stroke on my dinghy and I got up on a plane without trouble. I put a lighter weight 15hp 2-stroke on it and couldn't plane. I looked at the specs and it was because the 4-stroke develops more power at lower RPMs. It was a surprising result given the 2 stroke was lighter. I was the only person in the dinghy, the 4-stroke would easily plane with 3 of us in it. This is very dependent on your dinghy, we had a Carib which has a deep V hull on it. I'm sure a flatter dinghy would have been fine.

That is strange, since in a four 4-stroke power is produced once every 4-strokes of the piston, and in a 2-stroke power is produced once every 2-strokes of the piston. So, not only is a 2-stroke lighter, it produces twice the power. My observations have been just the opposite of yours. My 15 HP 4-stroke has problems getting up on plane when the dinghy is loaded, whereas my older 15 HP 2-stroke has no problems at all. The 4-stroke is also about 24 lbs heavier. Glad I kept the old motor that is going on 30 years old. It has never had any problems and always starts easy. I've never rebuilt the carburetor and I might have changed the plugs once in all those years. I do run some ethanol free fuel though it before I lay it up for the winter. Same for the 4-stroke. The newer 4-stroke has given me problems right from the start of ownership. It's often harder or finicky to start. The 2-stroke had much less parts in it, no valves or associated valve train, no oil sump, or oil. The 2-stroke can be field striped easily and has very simple reed valves that seem to last forever.

Still, I switched to 4-stroke for better fuel economy and to have a "clean" engine. That decision has worked out about as well as replacing my old Sears washing machine that cost very little to purchase and used 50 gallons of water, with a new high efficiency front loader that uses just a few gallons of water and cost more than my fist car. That new more environmentally correct washer runs for well over an hour, vs my old machine that ran for 20 minutes, and when I pull out my bed sheets, there are dry spots were the sheet did not even get wet. I may have made an environmentally friendly replacement decision, but now I have a solution that does not work very well in both cases.

I won't even get into the "environmentally friendly" new gas cans with no vents. You know the ones that results in more spills and difficulty in getting gas out of the stupid can........

[Kenpimentel]

Originally Posted by tdunlap

That is strange, since in a four 4-stroke power is produced once every 4-strokes of the piston, and in a 2-stroke power is produced once every 2-strokes of the piston. So, not only is a 2-stroke lighter, it produces twice the power..
..

I'm sure it matters which engines we're comparing. I think I had a Tohatsu 15hp 4 stroke and a Yamaha 15 2 stroke. I did find the respective power curves for each engine and that is what I saw. Again, I think the dinghy plays a big role in this experiment.

I had a zillion problems with fuel/clogging until I fitted a proper fuel filter on the back of my dinghy. I became an expert in tearing down and cleaning a carburetor. My biggest problem came from the crappy fuel lines that the ethanol ate. Once I switched to Ethanol free, best fuel lines and the filter, never another problem. No doubt the small jets in the carb are worse for these problems.

[Nicholson58]

Originally Posted by Scorpius

Is no one on here concerned about the environment? Two strokes are HORRIBLY polluting compared to four strokes.

We live aboard in the eastern Caribbean. I burn total 30 gal/year Gasoline. It doesn’t matter. A well tuned and maintained 2-st doesn’t puke and spit. Most of us are running ancient diesels that are far worse and consume more than the OB but still far less than one class 8 truck on a single haul. I have no car. I have no house. I buy 150 gal/year of diesel. Frugal use of cooking gas keeps us at 20-30# propane per year. Virtue signal all you want but reliability and ease of repair trumps all else. I really hate rowing an inflatable in 20 knot wind.

As far as I can tell, my Mercury Mariner 15 2-st is 50 pounds lighter than any replacement I can get in the Caribbean. It normally srarts on the first pull. Get a nice SS prop the proper pitch to maximize efficiency. The next thing, if you have a choice, get a motor that is the most common where you expect to cruise and need parts. In the Caribbean, Yamaha Enduro.

[Scorpius]

Originally Posted by Bycrick

I live full-time on the boat. I don’t have a car. Most of my electrical needs are supplied by solar. My carbon footprint, by comparison to most, is vanishingly small. But the do-gooders are going to try to tell me that I’m destroying the environment by using a 2-stroke outboard a dozen times a year. I’m supposed to sacrifice lightness and easy maintainability so that they can feel good about "saving the planet."

Nuts.

I believe I acknowledged the VERY low carbon footprint of those who live full time on their boats and do not have a home ashore - and my hat is off to you.

[FlyingScot]

I see more Enduro 15’s than any other single type by at least 2:1. That has to mean something.
If you do a lot of low speed motoring then I would likely buy a four stroke. But I hate to buy any four stroke that isn’t fuel injected. Does anyone make a 154TFI?

[tdunlap]

Originally Posted by Kenpimentel

I'm sure it matters which engines we're comparing. I think I had a Tohatsu 15hp 4 stroke and a Yamaha 15 2 stroke. I did find the respective power curves for each engine and that is what I saw. Again, I think the dinghy plays a big role in this experiment.

I had a zillion problems with fuel/clogging until I fitted a proper fuel filter on the back of my dinghy. I became an expert in tearing down and cleaning a carburetor. My biggest problem came from the crappy fuel lines that the ethanol ate. Once I switched to Ethanol free, best fuel lines and the filter, never another problem. No doubt the small jets in the carb are worse for these problems.

Yes, you are right. You have to be careful making comparisons. Generally though, if we are talking the same displacement (same cu/in), a 2-stroke is more powerful, without a doubt. However, there are other variables. A 2-stroke is generally designed and operates at higher revs where it produces better torque, whereas the 4-strokes are designed for lower revs and produce their torque at lower rpms. The prop is an important factor. It would be different for the two types.

In recent times the 2-strokes were designed for mixtures of 50-1 and actually were not the dirty engines of the past.

Two strokes seem to take a lot of abuse. When I was a kid, I worked in marinas every summer all the way through college. It was nothing unusual to see 2-strokes that were 20, 30 and more years old running just fine. I've found 4-strokes to work better if used often, but the 2-strokes seem to be able to sit around for ages, and if one was smart enough to run them out of gas before storing them, well they were easy to fuel back up, and they would start right up.

I think 2-strokes have many advantages, minis the fuel efficiency, and to some degree pollution. To be sure though, both types do produce pollution. Like someone else pointed out, as a life style, cruising folks tend to produce a lot less carbon than the average land based human.

So you just have to pick your poison based on your own preference. Electric, 2-stroke, 4-stroke, or oars. No one solution will be right for everyone. I would try to find a few people that have the actual motor you're considering, and ask about the service and reliability. Before you buy, ask to test it out for yourself to see how it preforms.

[DeValency]

Originally Posted by TrailerCruiser

Which is more dependable and easier to fix, a two-stroke or a 4 stroke? I'm looking for a 15hp short shaft outboard

If you can get a Yamaha 15HP, two stroke (Enduro), this is the best outboard money can buy. Super reliable, as light as 8HP four stroke that will live forever with a very little basic maintenance. Unfortunately, no longer sold in the US due to the EPA regulations.

[toolbar]

A new Yamaha Enduro 15hp is 40kg according to
all sources Iv found on Google. A new Tohatsu 15hp EFI 4 stroke it's 42kg. So what is this big issue about the super light 2 strokes?

There are some extremely light 15hp two strokes, eg Selva Naxos at about 28kg - but factoring in the supposedly bad reliability and the fuel thirst of that model, it didn't seem like a good option.

[Nicholson58]

Originally Posted by toolbar

A new Yamaha Enduro 15hp is 40kg according to
all sources Iv found on Google. A new Tohatsu 15hp EFI 4 stroke it's 42kg. So what is this big issue about the super light 2 strokes?

There are some extremely light 15hp two strokes, eg Selva Naxos at about 28kg - but factoring in the supposedly bad reliability and the fuel thirst of that model, it didn't seem like a good option.

Weights have come down a lot. That’s encouraging. My Mercury Mariner is about 75# that’s 34 kg

[malbert73]

Originally Posted by FlyingScot

I see more Enduro 15’s than any other single type by at least 2:1. That has to mean something.
If you do a lot of low speed motoring then I would likely buy a four stroke. But I hate to buy any four stroke that isn’t fuel injected. Does anyone make a 154TFI?

Yup tohatsu (I have one x 2 years and great) and Suzuki have 15hp 4 stroke EFI