2-Stroke vs 4-Stroke Outboards

[valhalla360]

Originally Posted by Funkydrum

On service intervals, I was surprised to see that valve adjustment is at 500 hrs (longer than I expected) and oil changes at 100 hrs.

Its less of an issue for a dingy that gets modest use but before we switched to a 4 stroke outboard for the mothership, it had a 2 stroke and sourcing oil was a minor issue. Not the end of the world but a hassle as 2 strokes become less common (and it's likely to get worse as the current one age out).

If you are staying in place, it's easy to run up to walmart in the car and pickup some 2 stroke oil but as you get away from easy sources, a lot of marinas don't carry it or only carry tiny bottles.

If you don't have oil for a 4 stroke when it comes time to change it, you can run an extra 10-20hr after hitting the limit and it's not going to cause any problems. Try not to do it but its not a big concern.

If you are out of 2 stroke oil, you are done until you can source some.

[DMCantor]

We used small 4-strokes in areas with a temporate climate and loved them. Quiet, fuel efficient, environmentally superior and a manageable weight.


Then we started cruising in the tropics, and it was one headache after another. Extremely sensitive to even small amounts of water in the fuel, constantly gumming up carburetors, hard starting, poor idle performance. Getting them running after a summer's layup was an adventure.



You see lots of 4-strokes in the Caribbean, but only in the 40hp and up sizes. That said, we never had any trouble finding someone to work on our 6hp 4-stroke - and we had lots of opportunities to go looking.


We traded up to a 8hp Yamaha Enduro 2-stroke and it has worked flawlessly for 6 years now.


So I do believe the choice depends on your cruising grounds.

[Bill Seal]

Originally Posted by valhalla360

Its less of an issue for a dingy that gets modest use but before we switched to a 4 stroke outboard for the mothership, it had a 2 stroke and sourcing oil was a minor issue. Not the end of the world but a hassle as 2 strokes become less common (and it's likely to get worse as the current one age out).

If you are staying in place, it's easy to run up to walmart in the car and pickup some 2 stroke oil but as you get away from easy sources, a lot of marinas don't carry it or only carry tiny bottles.

If you don't have oil for a 4 stroke when it comes time to change it, you can run an extra 10-20hr after hitting the limit and it's not going to cause any problems. Try not to do it but its not a big concern.

If you are out of 2 stroke oil, you are done until you can source some.

Far more 2-stroke motorcycles, chainsaws and (damn) leaf blowers than outboards. No reason to go to a marina.

[Cadence]

Originally Posted by Bill Seal

Far more 2-stroke motorcycles, chainsaws and (damn) leaf blowers than outboards. No reason to go to a marina.

Do they still make 2 stoke scooters? Maybe a Moped?
Outboards for small tenders make sense being 2stroke because of weight. 15HP and above not so much.

[Factor]

Originally Posted by Adelie

The issue is that in the US, Canada, the EU and maybe Australia it’s not legal to sell new, small 2-strokes because they can’t be made pollution compliant. Being that it’s illegal to sell new ones, I believe it is also difficult or possibly illegal to import parts for them. Given that this has been the case for some time the pool of mechanics that can work on the new 2-strikes is probably slowly shrinking.

If you can work on a 4 stroke engine you can easily work on a 2stroke.

If you leave the developed countries, the situation is reversed. Nobody buys 4-strokes so they aren’t stocked and nobody knows how to work on them. Slight exaggeration perhaps but close.

The single most prevalent motor in the South Pacific would be the Yamaha 25HP 2 stroke, but the 9.9 4 stroke isn't far behind

[Tupaia]

Originally Posted by Bill Seal

Far more 2-stroke motorcycles, chainsaws and (damn) leaf blowers than outboards. No reason to go to a marina.

Applies even in Europe the gardening lobby group were more assertive than the marine lobbyists. Just another example of green washing.

[goboatingnow]

Originally Posted by Tupaia

Applies even in Europe the gardening lobby group were more assertive than the marine lobbyists. Just another example of green washing.

Two stroke lawnmowers , ain’t seen one of those in decades. Two stroke you see in things like garden trimming equipment

[rslifkin]

Originally Posted by goboatingnow

Two stroke lawnmowers , ain’t seen one of those in decades. Two stroke you see in things like garden trimming equipment

Yup. At this point 2 stroke lawn equipment is mostly relegated to things that will be used at significantly variable angles (like chainsaws). Unless you go to an expensive (and heavy for small equipment) dry sump setup with multiple scavenge pumps, it's hard to make a lube oil sump work when you might have to flip the thing 90+ degrees in use.

[sailingharry]

Two comments:


* First Outboard oil is NOT chainsaw oil! Air cooled motors use a different oil than water cooled (and vice-versa).


* Second, we needed a <10HP (rated power) for our new aluminum RIB, and weight was very important as we manually lift in the davits at least twice a day and take the outboard off frequently. 4-stroke was in the 80+ pounds (but at 94, we could have gone to 15 HP - "illegal" but we seriously thought about it). We eventually bought a used 2017 Tohatsu 9.8 2-stroke for $475 on ebay. 5 years old, mostly in storage (he quickly decided he needed a 15, so it was a spare). Runs great, meets our needs, and weighs a featherweight 57lb! If it runs anything like the tired old 1992 8HP Evinrude 2 it replaced, I'll be set for another 30 years! Note, a bolt seized and sheared off in the lower motor mount, replacement part was easy.

[valhalla360]

Originally Posted by Bill Seal

Far more 2-stroke motorcycles, chainsaws and (damn) leaf blowers than outboards. No reason to go to a marina.

If you live shoreside and have a car, sure.

For a chainsaw or weed wacker, the tiny little bottles do the trick as it will take months to go thru a gallon of gas.

A 40hp outboard running 20-30hr per week, we were buying it by the gallon before we swapped out for a 4 stroke motor.

But a lot of those tiny 2 stroke motors have been swapped for electric, so they are a dying breed.

[valhalla360]

Originally Posted by sailingharry

* First Outboard oil is NOT chainsaw oil! Air cooled motors use a different oil than water cooled (and vice-versa).

Most chain saws are 2 stroke and use 2 stroke oil (the main exception being small electric models). They also use "chainsaw oil" to lubricate the actual "chain".

Since we are discussing the motor lubrication, yes, outboard and chainsaw use the same oil...I doubt anyone thought we were talking about outboard lower unit gear oil.

[ron17571]

My experience is that four strokes last longer. How available is two-stroke injector oil in various out-of-the-way places? I like both of them but considering limitations on two stroke outboards I would stick with a four-stroke. I think four-strokes use less gas also.

[sailingharry]

Originally Posted by valhalla360

Most chain saws are 2 stroke and use 2 stroke oil (the main exception being small electric models). They also use "chainsaw oil" to lubricate the actual "chain".

Since we are discussing the motor lubrication, yes, outboard and chainsaw use the same oil...I doubt anyone thought we were talking about outboard lower unit gear oil.

Well, when I get challenged, I research. And sometimes I come away confused....LOL.


Outboard oil is TC-W3. It supposedly is zero ash, for environmental issues. It also is designed to run at lower engine temperatures.


Chain saw/leaf blower oil (not bar oil) is TC. No "W." This is "low ash" and is also formulated for higher temps.


Conventional wisdom says they are different.


But then, some vendors, like this Walmart brand https://www.walmart.com/ip/Super-Tec...allon/16795065 says for outboards and all other 2-stroke. And there are users forums where people have been running TC-W3 in lawn equipment for years. But there are fewer links I found on the reverse (TC in outboards).


This article talks about snow mobile cylinder temps being north of 700F, while outboards are closer to 400. At the lower temperatures, TC oil can leave deposits. But the article isn't crystal clear on that.
http://www.comolube.com/wp-content/u...Snowmobile.pdf



And this discussion on RIBNET just adds to the confusion.
https://www.rib.net/forum/f50/2-stro...n-83097-2.html


Now I have no idea what to believe!

[moseriw]

Seems most of the people I see at the dinghy dock(s) frustrated over their engines not starting have 4 strokes hanging off the transom. Just saying

Oh yeahh says a victim of this 4 Stroke scrap

[nofacey]

Geez, if you’re headed offshore, get a 2-stroke!

I had a brand new 4 stroke when I departed offshore for 5+ years…..and I could COUNT on that mother’s carb fouling twice a year (and it was a bear to get at). Switched fuel tank, fuel line, added fuel filter….she was terrific when she ran, quiet, sipped fuel & had great power…..but in remote areas, she was a royal pain. Buddies with 4 strokes commiserated, those with 2 strokes just smiled. 2 strokes are way more fuel tolerant, and hence more reliable.