Two stroke or four stroke

[a64pilot]

If your careful, the carburetor issue can be mitigated.
I’ve had this for at least five years, and it’s been stored for long periods at a time, and I’ve never cleaned the carb, and I can’t imaging a smaller carb than this.

[Cadence]

The only thing wrong with carbs is running them on corn oil or some of what they call gas today. As a kid my little brother and I ran the hell out of a 3HP Johnson on marine white without problems for years.

[Ken Pole]

I run a Lehr 2.5HP four-stroke propane O/B on my tender, which is about the same size as yours. About 50lb/23kg(long-shaft versions are slightly heavier), which I easily lift with one hand. It won't get up on a plane but that's no big deal unless you find yourself a huge distance from a landing site. Here's an independent review: https://www.thoughtco.com/lehr-propa...review-2915368

[refuge]

This all depends on what duties you expect your dinghy to perform.

First of all, 2-strokes are not illegal and they will never be illegal. Modern 2-strokes like E-Tech’s actually surpass 4-strokes in emission standards and noise. Not to mention they are considerably lighter and more powerful with a stronger hole shot and faster top speed.

For my RIB I max out or even exceed the rates HP called for by the dinghy manufacturer. Currently I have a 12’ Caribe with a Nissan 50 two stroke. My dinghy can do 45 mph. While I don’t always go that fast, when I have 6 people and all their gear, I can still cruise at 35 mph without even working the engine. That may not be a priority for people but it is for me. When I drop anchor I take the dinghy and go explore. I might put 100 miles on it in a day snorkeling different places. And once I had to make an emergency trip back to Florida from Bimini. It was calm so I zipped across the stream and shot back the next day.

Weight is a big issue. Especially on a small boat. 2-strokes are about 25% lighter. That means more speed and more efficiency. Modern 2-strokes are also just as fuel efficient as four strokes.

4-strokes are nice. I like them in motorcycles and other equipment, but not on a dinghy. 4-strokes require more maintenance too. Oil changes and more moving parts.

But if you want speed, power, and simplicity then a 2-stroke is mandatory.

[refuge]

This all depends on what duties you expect your dinghy to perform.

First of all, 2-strokes are not illegal and they will never be illegal. Modern 2-strokes like E-Tech’s actually surpass 4-strokes in emission standards and noise. Not to mention they are considerably lighter and more powerful with a stronger hole shot and faster top speed.

For my RIB I max out or even exceed the rates HP called for by the dinghy manufacturer. Currently I have a 12’ Caribe with a Nissan 50 two stroke. My dinghy can do 45 mph. While I don’t always go that fast, when I have 6 people and all their gear, I can still cruise at 35 mph without even working the engine. That may not be a priority for people but it is for me. When I drop anchor I take the dinghy and go explore. I might put 100 miles on it in a day snorkeling different places. And once I had to make an emergency trip back to Florida from Bimini. It was calm so I zipped across the stream and shot back the next day.

Weight is a big issue. Especially on a small boat. 2-strokes are about 25% lighter. That means more speed and more efficiency. Modern 2-strokes are also just as fuel efficient as four strokes.

4-strokes are nice. I like them in motorcycles and other equipment, but not on a dinghy. 4-strokes require more maintenance too. Oil changes and more moving parts.

But if you want speed, power, and simplicity then a 2-stroke is mandatory.

[sv Stella Maris]

Hi Champo,

I doubt you ever get to these last posts, hehe.

I’ve rebuilt many of both (how I used to fund my motorcycle racing).

2 stroke: less moving parts, more fuel, less weight, less costs

4 stroke: more moving parts, less fuel, more weight, more cost

BOTH have appropriate applications over the other.

ALL Carbs can have quirks. Some new 4’s have fuel injection.

From current experience, I would not purchase a new Honda.

[Firehoser75]

Champo,
I used to own a Nissan 6hp 4 stroke engine. I religiously did all winterizing and maintenance, but every spring the thing would not start. The problem was left over fuel (with ethanol) gumming up the very small jets in the carb. Strip and clean the carb, and it was good to go. The RIB would plane with one person, but not with two.
Now I use a Yamaha 8hp 2 stroke. Again properly winterized and maintained. No problems. Starts right up within about 3 pulls every spring, planes the RIB even with two people and groceries, and is light enough for me to handle fairly easily. Mixing gas is not a big deal, especially compared to either the work to strip the carb or the cost to have it done!

Regards,
Tom

[secrabtree]

We've had both 2 and 4 strokes in about 6-10 hp. 2 stroke is lighter for the same power. But we could explore small rivers and creeks at slow speed almost silently with the 4 stroke and thus see more wildlife. The 2 strokes, at that slow speed would be much noisier and the plug(s)would foul. And a big plus is that we could go considerably further without having to refuel. Some of the other comments said that the 4 stroke consumed only a little less fuel than the 2 stroke. The comment either didn't state ngne power or was comparing a 15 hp 4 stroke with a 9.9 hp 2 stroke - and the 4 stroke STILL burned less than the smaller 2 stroke.

[Coast Wanderer]

We currently have an old 15hp Evinrude 2 stroke for our 8' dinghy. We have just been hoisting it up onto the swim grid, but we are going to go for a Tohatsu 6hp 4 stroke for a few reasons. It's a bit lighter than the old 15, I don't need to mix or store 2 stroke fuel on board, The 6hp Tohatsu has a built in gas tank for those short marina store runs, but (they actually run for quite a while on that) my big 2 stroke tank can go home and be used for other 2 stroke tools etc and since I have a pair of gas burners for engines, I see it as a good thing to have a little extra gas on board, even if I never need it for the main engines, but may be able to help someone else. I may even buy another smaller tank for the dinghy, just for longer trips.
I can tell you that a dinghy with a 15 hp motor on it can really get going, but my wife doesn't love wild dinghy rides when taking the dog to shore for a stroll...
You know she's serious when she suggests getting a "more manageable motor" for the dinghy..

[ZULU40]

Originally Posted by Dockhead

There's lots in the archives on this for the OP.

I have come around to not caring so much anymore about the differences. The current generation of four strokes are not really much if any heavier than two strokes.

I love two strokes, find them (contrary to what someone above posted) to be smoother and easier to start than four strokes. Love their simplicity. But in my experience, my particular four stroke outboards have been vastly more economical than the two strokes I used to use -- I think about half the fuel burned. Maybe my two strokes were all set up rich -- I don't know.

So if I were buying a new outboard, in a place where I had a choice, I think I would just buy what is lighter and/or cheaper providing it's good quality.

Or go electric, depending on the use case. I'm thinking about Torqeedo myself. In addition to an IC powered outboard, but probably what will be used 90% of the time considering how I use my dinghy.

This makes complete sense, for myself I went with the fewer parts and more power per weight of a 2 stroke, simplicity in maintenance and an engine that is therefore easy to fix without special tools.

I threw the onboard fuel tank away as it was rusty anyway, and just use a fuel tank in the dinghy, so its even lighter to haul aboard the boat. Its a 5hp Yamaha, the fuel is 100:1 mix, the 9.9hp also have a good reputation but my dinghy maxes out at 5hp.

Does it smoke, sometimes yes a tiny bit at idle, zoom off and you wouldnt know the difference. Injected 2 strokes by Mercury are said to have better fuel consumption than 4 strokes.

[Kenomac]

Originally Posted by medevicerep

Be careful, two stroke engines are becoming illegal in some areas due to emissions.

They’re not “illegal” to own and use anywhere, they’re just not available to be sold new due to the EPA emissions requirements.

[Visarend]

In 40 years, I had 2 strokes (2, 4,6,7.5, 10, 25 HP) and 4 strokes (6 Yamaha, 5 Suzuki). For weight reasons and ease of maintenance IMHO I would search a very good 2 stroke Evinrude/Johnson 4-6 HP from the late 70s or 80s - very low cost, 2 cylinders (ca 80 cc the 4HP, ca 120 the 6), sturdy no frills engines (and usually not stolen).

[Pete7]

Originally Posted by sv Stella Maris

From current experience, I would not purchase a new Honda.

What's wrong with the little 2.3hp Honda? The carb looks and works in a very similar manner to the little OMC 2.3 and 3.5hp engines.

Not having a water pump is one less item to worry about.

Pete

[bradm85]

I have gone to electric with a Torqeedo. It's light and equivalent to a 3 hHP OB. It is pricey, but I have a spare battery and I can charge them with my 12 vDC plug and have never had an issue running out of power. epropulsion makes them too and offers a more power one equal to a 9.9 HP. Here again, they are pricey, but at 62 they are so light and easy to handle they are perfect for my dinghy.

[sv Stella Maris]

Originally Posted by Pete7

What's wrong with the little 2.3hp Honda? The carb looks and works in a very similar manner to the little OMC 2.3 and 3.5hp engines.



Not having a water pump is one less item to worry about.



Pete

Sorry Pete, my mistake. I was, albeit failed, meaning bigger Honda 4 stokes. The little 2.3hp Honda I did just see at anchor by an older woman who was a huge fan of it for ease of use.