2 stroke vs 4

Israel Hands

Super Anarchist
3,174
1,866
coastal NC
look at this baby! 2 hp evinrude from what 196?. guy has it on an inflatable. look at the castings on this little gem...that's a throttle lever! adjust the mix and idle, love the htree point transom bracket.

View attachment 538605
I have one just like that only it’s Johnson! Put it on my Walker bay. I mainly got it because it reminds me of the 1.5 evinrude with a rope cord that I had as a little kid in the 60s
 
Didn't read it all, but weight is a huge one in favor of 2 stroke. If you are always doing the dock thing it's not as bad, but once you start moving, manhandling the outboard gets more and more common. Dragging up on a beach even with wheels, stowing on the boat, extra weight on davits if you leave it on etc etc. We have a 9.9evinrude, tohatsu 4s. Same weight as a 2S 15. The newer models. If we went down to a 8 2s same power in dingy but much less hassle. The outboard cranes are good in concept but useless in anything other than protected flat Anchorage. If you go bigger RIB the 15 2s seemed to be the best choice, smaller whatever the 6-8 2s.
 

Russell Brown

Super Anarchist
1,757
1,429
Port Townsend WA
There'a good reason we can't buy 2-stroke outboards in this country. A bit of extra weight is a small price to pay to avoid dumping oil directly into the water. I've had 2-strokes and liked some things about them, but even without the pollution aspect, the extra fuel use isn't attractive.
 

Dilligaf0220

Super Anarchist
1,906
185
Not The Caribbean
There'a good reason we can't buy 2-stroke outboards in this country. A bit of extra weight is a small price to pay to avoid dumping oil directly into the water. I've had 2-strokes and liked some things about them, but even without the pollution aspect, the extra fuel use isn't attractive.

Reread my last post on the page before in this topic. 2-strokes of 2020 were not the 2-strokes of 1970.

No blue haze, no rainbow on the water at the dock. The big bore direct injected motors actually emitted less than 4-strokes.
 

Russell Brown

Super Anarchist
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1,429
Port Townsend WA
Besides the 4's being a bit heavier and more complex, what is the reason to want a 2-stroke? I've had a lot of experience with both and far prefer the 4-strokes. Is it because someone decided they're bad for the environment and outlawed their sale in this country. Anyone familiar with the book "Polluting for pleasure"? As I understand it, that book caused the change.
 

El Borracho

Verified User
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Pacific Rim
Besides the 4's being a bit heavier and more complex, what is the reason to want a 2-stroke? I've had a lot of experience with both and far prefer the 4-strokes. Is it because someone decided they're bad for the environment and outlawed their sale in this country. Anyone familiar with the book "Polluting for pleasure"? As I understand it, that book caused the change.
Oil in the fuel, and thus the exhaust, is the major problem regardless of the number of strokes. 2-strokes have the added problem and expense of unburned fuel in the exhaust. Not a good look leaving an oil slick in the crystal clear waters of an idyllic lake or tropical paradise.

In theory 2-strokes are noisier from exhaust and intake noise. However the newer air cooled 4-strokes are very noisy too.
 

Max Rockatansky

DILLIGAF?
4,031
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And I’ll reiterate that extra weight causes drag and slows the mother ship down, also lower power means the dinghy runs for longer. Thus costs fuel and pollution from the larger perspective.

Besides the 4's being a bit heavier and more complex, what is the reason to want a 2-stroke? I've had a lot of experience with both and far prefer the 4-strokes. Is it because someone decided they're bad for the environment and outlawed their sale in this country. Anyone familiar with the book "Polluting for pleasure"? As I understand it, that book caused the change.
Please review prior posts in this thread, several of which have answered your question
 

kent_island_sailor

Super Anarchist
27,659
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Kent Island!
Marine Biodegradable 2-Stroke Engine Oil is a rapidly biodegradable product as demonstrated with the ultimate biodegradability test. Marine Biodegradable 2-Stroke Engine Oil is NMMA TC-W3™ and European Eco-label registered.

FYI
 

eastbay

Member
390
18
Oakland
Marine Biodegradable 2-Stroke Engine Oil is a rapidly biodegradable product as demonstrated with the ultimate biodegradability test. Marine Biodegradable 2-Stroke Engine Oil is NMMA TC-W3™ and European Eco-label registered.

FYI
Seems an excellent solution! Didn’t know that existed.

Now if they made it steak sauce flavored so it could do double duty….
 

2airishuman

The Loyal Opposition
1,000
466
Minneapolis area
Besides the 4's being a bit heavier and more complex, what is the reason to want a 2-str

It depends. In the 3HP and less range, IMO having used both, the case for a 2-smoke is that they have less vibration and can be stored and transported in any orientation; the case for a 4-stroke in this size range is that they use half the fuel and thereby simplify fuel logistics -- though this is weak sauce for engines that burn less than a gallon a day in plausible use cases. In my view the Suzuki DF2.5 (a 4 stroke) is compelling in this space, there's no weight penalty, and the benefit in the fuel logistics area makes up for its other failings. That said I have a 2 smoke and have not replaced it (yet).

In the 15 hp size range, which is what everyone with a deflatable dinghy seems to want, the benefit of a 2-smoke is that you can (in the Caribbean) get a 2-smoke Yamaha Enduro that weighs 84 pounds while the lightest 4-stroke 15hp sold in the USA weighs 105 pounds. For many people the difference between an 84 pound dingy motor and a 105 pound dinghy motor is the difference between "can reasonably get off the dinghy and onto the rail" and "can't." That, in a nutshell, is the reason Caribbean cruisers want 2-strokes.

Most buyers of 15 hp outboards in the USA don't give a flying fuck whether the engine weighs 84 pounds or 105 pounds because, at most, they take it off the boat once or twice a year and either way they need a hoist or two people. Cruisers with deflatable plastick dingies are a tiny fraction of the the addressable market for outboard motors. Otherwise, if Suzuki/Yamaha/Honda/Tohatsu product management cared deeply about winning the battle for the lightest 4-stroke 15 hp motor, they could build one that weighs less than 84 pounds. People might not like the price and in particular the guy fishing for flathead cats with stink bait in Missouri probably won't pay extra for a motor that is 21 pounds lighter. And there are a lot more people fishing for cats who buy outboard motors than there are cruisers.
 
It's a worthy argument to look at your footprint. It's why I bought the 4 stroke hernia factory I have. I would love to have one of Russels boats with a little 4 stroke but it's didn't happen last go around, don't play the lottery... It's a complex issue with lots of considerations. The fact most people near water dump more crap from their car brakes in water is worth noting. That's from the kids middle school science project on Orcas building a bioswall. Cruising is about making life choices that reflect alot on you, not advocating dumping oil in the water but the macro view on use and impact is not a clear line and there is definitely room on all ends.
 

2airishuman

The Loyal Opposition
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Minneapolis area
It's a worthy argument to look at your footprint.
For many years in a land-based lifestyle I burned 1800 gallons of gasoline a year to run the cars and 1500 gallons of propane to heat the house. I knew, and it was obvious, because I had to get both the gasoline and the propane by the truckload and store them in tanks on the rural property where I lived.

Now I have an electric car and a smaller house and go through somewhat less fuel.

I don't think even the fairly serious year-around cruisers put that many hours on their outboards. 200 hours a year? Maybe 500 for a rare few? 15 hp 4-strokes burn 1.5 gallons an hour, 2-smokes twice that. So even with a 2-smoke the amout of fuel burned is small relative to typical land-based lifestyles. Some localities are more susceptible so we have the SCAQMD etc. Focus focus, the PVC in a short-lived inflatable has environmental impact too.
 

hberg

New member
Marine Biodegradable 2-Stroke Engine Oil is a rapidly biodegradable product as demonstrated with the ultimate biodegradability test. Marine Biodegradable 2-Stroke Engine Oil is NMMA TC-W3™ and European Eco-label registered.

FYI
Woah this is new to me. Any experience with it? For that matter, I wonder if there is a big difference in outboard longevity between various brands of 2 stroke oil?
 

loneshark64

Super Anarchist
1,515
1,351
Maine, USA
So, my 1980s Yamaha 6 died this June a week before a trip. Having already spent a fortune on boat stuff this year I didn’t want to spend $2000-3000 on an outboard immediately. So I bought a $220 Chinese two stroke motor on Amazon. I figured I was only dinghying short distances to and from docks on that trip so if it sucked I could row. It arrived in the mail 3 days later.

I will say up front that this motor is an atrocity. Stylistically it is an offense to the ancient and sacred sailor-y way of doing things. It is loud, smoky, and poorly made. It will not last. I immediately took it all apart and sprayEd everything with anti corrosion stuff.

I just love the thing though. It weighs about 12 pounds and I can lift it on and off the dinghy with one hand. The gas tank is part of the motor, so no separate tank. It is air cooled so it is smoky but it’s not dumping oil in the water. Basically it has the same motor my gas weedwhacker has so you prime it by pushing the bulb 10 times and it starts right up with a couple pulls, and uses little fuel. Like the weed whacker it is stupendously loud. But it pushes my 12 ft hard floor inflatable with 2 big guys in it just fine.

On that trip, with a group of other boats from the yacht club, the first time i pulled up they looked at me like WTF and laughed til they cried. I couldn’t blame them. But it works, and it’s light.

Next spring I will buy a properly respectable outboard but I am keeping this as a backup and will still absolutely use this quite a bit for quick trips where I just want to toss an outboard on the boat. I am thinking about making a little muffler for it.
EB250B3B-EEB1-4D1B-9D98-FD45CF9583F2.jpeg
 
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thinwater

Super Anarchist
1,062
144
Deale, MD
Lots of strong opinions. I've had three 2-stroke and six 4-strokes over the years.
  • Starting. About the same, since I have very, very little trouble with either. Maintain your fuel properly.
  • Weight. I always kept the dingy on davits, so who cares? If I had to haul the dinghy on deck, I would use a kayak. I wouldn't go through the haul-on-deck routine unless it was a paid job.
  • Mileage. At least 30-40% better with the4-stroke. How important that is depends on the use.
  • Noise. Considerably less, which again depends on the use. But I like quieter better.
  • Durability. Those that failed (not sold with boat) did so because of corrosion. Nothing to do with the 2- vs 4-stroke debate.
  • Fixing fuel. Trivial task. I use an anti-corrosion addtive (Biobor EB) either way.
  • Parts. Never had a problem. All Merc/Yamaha/Tahatsu motors. Only a few parts, though. Mostly maintenance impellers, plus a few fuel connectors and a few carb kits for new-to-me motors that had not been loved.
For dinghy use, I don't think it's worth a strong opinion. We don't run them that much and they all work.
 

chester

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