2 stroke vs 4

[hberg]

Hello! We cruise in the PNW but am planning to go further afield in the next year or so and need a new outboard on the dinghy. Looking at pros/cons for 2 stroke versus 4. The make will probably be Tohatsu/Nissan/Mercury and looking for 5-9 hp. Price/condition are really the only factors aside from 2 vs 4. The lower weight is attractive for 2 strokes as for the same 60lbs weight we could get an 8hp in place of a 4 or 5hp 4 stroke.

For the cruisers out there - has one stood out over the other as being easier to fix while cruising outside of the US? Is it particularly annoying dealing with mixed fuel?

And emissions. It seems well known that 2 strokes produce more (quantity) harmful emissions, due to mixed fuel so oil is being burnt/expelled & also the frequency gas is added in the fuel cycle. This is true for large outboards I'm obviously convinced but it so bad for these little 6hp outboards as well? Or do they turn out to be about the same? Can't find any distinctions online.

Thanks for your input!

 

[Atlantic Posse]

from what I've experienced
noise and smell are 2 stroke downsides
weight is the downside for 4 strokes

 

[socalrider]

2 strokes which are not fuel injected are horrific polluters of waterways and have been banned in many places for very good reasons. A substantial portion of the premix you put in the tank ends up in the water - like 10-20%. No bueno.

I don't think a fuel injected low-emission 2-stroke in the 5-9hp range exists. That's always seemed like a weird hp range for me, as it's often not enough to get anything up on a plane reliably, so functionally the same as a 2-4hp. If you don't care about planing, give the e-propulsion Spirit a look. It's like a 2hp but you can charge it off 12V overnight so no gas on the boat & no carb issues ever.

 

[toddster]

FWIW, I picked up a Craigslist 9.9 Johnson (Suzuki) 4 stroke a few years ago, and couldn't be more pleased with it. It IS a little heavy, and there's the (optional) battery to deal with ( but it also powers a little chart plotter/fish finder and charges phones, VHF's, etc.). So far, it always starts easily (just like the 2-strokes) whether started with the battery or the pull rope.

 

[lom]

FWIW, I picked up a Craigslist 9.9 Johnson (Suzuki) 4 stroke a few years ago, and couldn't be more pleased with it. It IS a little heavy, and there's the (optional) battery to deal with ( but it also powers a little chart plotter/fish finder and charges phones, VHF's, etc.). So far, it always starts easily (just like the 2-strokes) whether started with the battery or the pull rope.

By 'Johnson (Suzuki)'... Are Johnson motors Suzuki blocks? I thought Johnson was like the one American made brand? That'd be good to know as there are a few of those in the area and I wrote those off originally as people on the docks have talked of them being bad luck and hard to get parts for

 

[toddster]

All "brands" are pretty much fictituous properties of holding companies. You Pays a Fee and you can slap that brand on your shit.
IIRC, when Bombadier bought up Johnson, they were going to sell 2-strokes as "Evinrude" and 4-strokes as "Johnson." But they didn't have tooling for the lower HP sizes and they rebranded Suzuki's in those cases.

 

[lom]

All "brands" are pretty much fictituous properties of holding companies. You Pays a Fee and you can slap that brand on your shit.
IIRC, when Bombadier bought up Johnson, they were going to sell 2-strokes as "Evinrude" and 4-strokes as "Johnson." But they didn't have tooling for the lower HP sizes and they rebranded Suzuki's in those cases.

That is wild but makes sense after learning of all the shared blocks and parts and whatnot. Good to know! Kinda sounds like whatever deal is available they're all the same thing almost

 

[Max Rockatansky]

For us, the light weight (75lb 15hp) and simplicity of an old (1988) Evinrude 2-stroke win the day. Not banned except in ‘the West.’

Plenty 2-strokes being purchased from the Bahamas, the 15hp Yamaha is a favorite. The newer engines do run cleaner than they used to.

OMC was bought out by Bombardier in 2000, so there is your year standard

 

[Ajax]

but it so bad for these little 6hp outboards as well? Or do they turn out to be about the same?

The bottom line is, it depends upon your conscience.
2-strokes pollute more and you know this. You'll simply have to decide where your line of tolerance lies (and I'm not here to judge you).

Setting aside the environmental concerns for a moment, think of the logistics. You'll have to carry 2-stroke oil with you as well as gasoline. If you go 4-stroke, it's one less bottle of nasty shit that could leak somewhere in the boat, one less item that you need to source and carry.

I prefer electric propulsion not only for the environmental reasons but the logistical reasons. I already have to carry diesel and propane. I don't want to have to carry gasoline, too. With enough solar capacity, I can make my own fuel. The trade off is range and speed. For MY use case, the trade off is acceptable. For a lot of people it's not, and I understand that.

 

[221J]

4 strokes are more fuel efficient and smoother running.

 

[El Borracho]

FYI: Both 2-and 4-stroke engines might use oil-fuel mix (and v.v. ?).

I sure don’t like the oily sheen on the water that mixed fuel can cause. But the power to weight advantage is considerable.

 

[Sail4beer]

Always had 2 strokes like the Nissan 3.5 and Johnson Seahorse 5hp until my 2.3 Honda, air cooled 4 stroke. Great little motor. and better on fuel than the 3.5hp 2 stroke.

Also, I have a brand new, unused Torqueedo 1103 long shaft with bags, etc, that I’m not going to use because it’s too difficult to reach on one of my boats. I’m going to list it in the classifieds tomorrow after I take some pics. Big discount too!

 

[kent_island_sailor]

I am a 2-stroke fan, I have an Evinrude 15 HP and a Yamaha 15 HP 2-stroke. They are much lighter than any 4-stroke of that HP. The oil doesn't leak out of them if you set them at the wrong angle. They are easier to salvage if drowned.
That said, in the USA at least you are talking about buying old engines, probably 20+ years old.
Suzuki seems to have made some progress at lighter 4-strokes, so if I were buying a new engine I would start there.
Also think on the use case: My 15 will get the dinghy to 18-20 knots with a good load. When I had a 6 HP engine it would get up on plane with just me, but not with any additional passengers. My 15 also makes for a good tug, I can move a pretty big boat in calm weather. If engine shopping now I would get the biggest engine that would fit or the smallest engine. If tugging and high speeds with heavy loads are not going to be a thing, the lightest little engine will do, you're going hull speed anyway.\
Edit - the OTHER big thing - does the engine stay on the dinghy? My engine comes off in December and on in March. I don't have any easy way to get a 70+ pound engine on and off a dinghy, if I was doing that I would have the lightest engine I could find!

 

[kent_island_sailor]

This little guy weighs 29 pounds

Suzuki 2.5 HP DF2.5S5 Outboard Motor

Suzuki's 2.5hp model DF2.5S5 outboard motor is a perfect choice for square stern canoes, small tenders and inflatables as well as other small craft. At only 29 lbs, it's the lightest 4-stroke Suzuki outboard ever built.

onlineoutboards.com

 

[Ajax]

This little guy weighs 29 pounds

Suzuki 2.5 HP DF2.5S5 Outboard Motor

Suzuki's 2.5hp model DF2.5S5 outboard motor is a perfect choice for square stern canoes, small tenders and inflatables as well as other small craft. At only 29 lbs, it's the lightest 4-stroke Suzuki outboard ever built.

onlineoutboards.com

It has an internal tank, which is nice and the price is good as well.

 

[kent_island_sailor]

Here you go: This 15 is 22 pounds heavier than my 15, but it isn't 25 years old and seems lighter than most new engines:

Suzuki 15 HP DF15AS4 Outboard Motor

Suzuki's all new fuel efficient 15hp EFI four-stroke is an excellent choice of power for medium to larger sized jon boats, skiffs, and inflatables. It comes with your manual start and offers tiller steering with a 15 inch short shaft. As the lightest outboard in its class at 97 lbs. and one of...

onlineoutboards.com

Notice the 20 weighs the exact same amount:

Suzuki 20 HP DF20AS4 Outboard Motor

Suzuki's all new fuel efficient 20hp EFI model DF20AS4 four-stroke outboard with the manual rope start and 15 inch shaft is an affordable choice of power for medium to larger sized jon boats, skiffs, and inflatable boats.. As the lightest outboard in its class and one of the quietest 4-strokes...

onlineoutboards.com

 

[eastbay]

With these little non-injected 2 strokes you might as well just pour the mixing oil directly into the water. If you're comfortable doing that then do it. You're announcing to the world and the other people at the dinghy dock that you care only about yourself and not the waters we sail in.
There was a news video where they ran a small two stroke in some Lake Tahoe water in a clear tank for a few seconds, it was disgusting what it did to the water. Afterwards they wouldn't let them pour the water back in to the lake! (this was before the ban).
Several years ago I got in a bit of a shit storm here for confessing that I use the bucket and chuck or direct deposit method for disposing of shit on my little head-less F242 while cruising in remote areas. I don't believe there is any comparison between the damage done by the odd turd in open water versus the oil pollution from 2 smokes- that smoke is unburned oil/fuel and goes straight into the water.

 

[Raz'r]

If it's not a planing dinghy, and you don't need to motor for hours on end, electric.

 

[lom]

Here you go: This 15 is 22 pounds heavier than my 15, but it isn't 25 years old and seems lighter than most new engines:

Suzuki 15 HP DF15AS4 Outboard Motor

Suzuki's all new fuel efficient 15hp EFI four-stroke is an excellent choice of power for medium to larger sized jon boats, skiffs, and inflatables. It comes with your manual start and offers tiller steering with a 15 inch short shaft. As the lightest outboard in its class at 97 lbs. and one of...

onlineoutboards.com

Notice the 20 weighs the exact same amount:

Suzuki 20 HP DF20AS4 Outboard Motor

Suzuki's all new fuel efficient 20hp EFI model DF20AS4 four-stroke outboard with the manual rope start and 15 inch shaft is an affordable choice of power for medium to larger sized jon boats, skiffs, and inflatable boats.. As the lightest outboard in its class and one of the quietest 4-strokes...

onlineoutboards.com

This is likely due to it being the same engine but with a different carburator/higher rev limit/higher compression right?

Issue with these are they're $3000 not $700 but otherwise that is a good point. Even in older ones the weight across different models follows this on occasion

 

[kent_island_sailor]

This is likely due to it being the same engine but with a different carburator/higher rev limit/higher compression right?

Issue with these are they're $3000 not $700 but otherwise that is a good point. Even in older ones the weight across different models follows this on occasion

Speed costs money, how fast do you want to go
My ancient USED engines cost over a grand each, so even used speed is not cheap.
As for the engine weight, there are usually 2 or 3 different horsepower levels per block, so you can compare weights and get the most powerful at the same weight