Two stroke or four stroke

[stainless guy]

When I was younger it's was all two strokes, now that I am a bit older 4 strokes seems to be the style.
waay smoother, not nearly as messy and 4strokes will run from dusk till dawn. ..

[waterman46]

Originally Posted by champo

Hi,

First ever post so be kind.

Looking to buy a new motor for my 2.6m inflatable tender and trying to decide between a four stroke and a two stroke (while they're still available)

Two stroke appear to be lighter, perform better and are more affordable so should be a no brainer right?

Anyone out there made the change to four stroke? Was it a good move? Are they worth the extra investment?

Please tell us what max HP your dinghy is rated for and is it RIB or not? RIB is heavier, need more HP than roll-up or inflatable floor. RIB needs 15HP, but 10HP is fine for lighter dinghy. And what's your dink driving style and needs, ie. do you need a high speed planing dink or are you OK with putting around slowly?

We had Evinrude 10hp 2stroke on Zodiac dinghy (not RIB, just sections of plywood that formed an internal floor with an inflatable V bottom) and it was a very light craft that got up to plane with two adults and one child. Dink could be easily hoisted and stored on foredeck, even with motor mounted, using spare jib halyard. Loved the Evinrude but did not like having to mix the gas with oil properly.

Then we got us a RIB to handle bigger chop and drag up on rough beaches - love it, but needed 15 HP so we got a 4 stroke Honda, used. Great motor, super quiet, smooth, no smoke, no having to mix oil with gas. But now have to do oil changes - bit of a hassle but once a year is enough. The heavier motor can only be put onto the dink by using a block and tackle, and we added davits to hoist the heavier RIB.

[Sojourner]

The PO of our boat left us a 15 hp 2 stroke mercury.... the thing ate gas, noisy as hell, and refused to start half the time. Fixed it up, winterized it, stuck it in the transom as a spare, and bought a 20 hp 4 stroke. Didn't have much choice what to buy here in the EU, everything is 4 stroke that I saw. Yeah it's 10kg heavier than the Merc, but that's what an outboard davit is for. It starts on the first half of the first pull every time...and that's worth its weight in gold

[RaymondR]

Originally Posted by Akapeterc

Two-stroke motors can’t be sold in Australia after about halfway through next year

More self righteous, hypocritical, virtue signalling twaddle.

I am in Gladstone harbour having passed half a dozen or so monster coal and LNG carriers. I would bet my next carton of beer that these all have two stroke, oil burning fuel engines.

The two stroke engines in these monsters have two oil systems, one to lubricate the bearings and which would not require much in the way of oil consumption, and a second for combustion cylinder lubrication. It's the second one which is the nasty as it's "sacrificial" and the lube oil gets burned and spewed out the exhaust.

Each one of these on it's voyage to northern Asia probably burns more lube oil than the entire fleet two stroke motors in Australia.

Be aware that this anti-two stroke nonsense will also catch the lawn mowers, whipper snipers etc. as well as the low horsepower outboards wherein weight, cost and practicality tend to be more important factors then the increase in fuel efficiency.

[Ip485]

Two stroke.


I have tried two and four.


As others have said, two stroke are lighter and offer greater power to weight ratio.


Even more importantly, I have found two strokes handle far more abuse, especially not being run for a period, and still start without issue. This was ultimately the deciding factor for me, as nothing is more annoying than an engine that doesnt start after a winter lay up.

[valhalla360]

What HP engines are you looking at and what are your performance expectations?

If you are trying to get on plane with a 4-6hp engine every ounce is beneficial.

If you are trying to get on plane with a 15hp engine, it shouldn't be a big deal for either engine type and the 4 stroke has much better efficiency.

If you just want to put along a displacement speeds, even very low HP 4 strokes are fine.

As someone mentioned, once you get above around 6hp, a lot of people are going to be looking at some form of hoist to get the motor on and off.

[Pete7]

Originally Posted by RaymondR

More self righteous, hypocritical, virtue signalling twaddle..

Bit strong, I think you will find he meant the smaller 2 stroke engines. Happened in Europe about a decade ago for leisure users which has now created an interesting second hand market for old 2 strokes many of which are now selling for more than the original purchase price.

I have just switched to using a little Honda 2.3 which so far is proving quite useful on a 2.7m inflatable. The great thing is that I can lift it with one hand from the dinghy on and off the yacht. It will just plane with one person but we don't do long passages in the dinghy, its more for crossing estuaries or harbours.

Pete

[valhalla360]

Originally Posted by Reefmagnet

I'm weird. Nothing reminds me more of being on the water then a whiff of good ol' two stroke exhaust, which kind of smells pleasant because of the association.

You aren't the only one.

Only difference is it reminds me of snowmobiling. As a kid, dad would put me in front of him and my face was right up next to the carb.

[Luc bulterys]

Normally I keep low profile and rarely react on posts, but some of the above advices really chocked me:
Isn’t it the ultimate experience for us cruisers spending quality time in beautiful places on the water, as far away as possible from exhausts and pollution of all kind … One of the horrific moments in the anchorage you share, is such a two stroke passing by, leaving his toxic fumes behind, all because this offers a few practical advantages.
And stop thinking that it won’t make a difference, or because others pollute even more. So please, at least consider it in your choice, if not for your own peace of mind, do it for your fellow cruisers who do care and just want to fully enjoy the beautiful environment.
And, as some have suggested already, if you’re willing to invest in a better environment and really ease of use, look also for electric. Lots of choices these days.

This is the opinion of a fellow cruiser who’s hoping more and more people will make eventually the changes we need.

[a64pilot]

Everyone keeps going back to weight, which is a real issue.
However that depends on size, the 20 HP Zuki is “Only” 99 lbs.
Find me a 20 HP two smoke that weighs in at 99 lbs?
BTW, that is 5 lbs per HP.
Someone check my numbers, but I believe the venerable 15 HP Yamaha Enduro is 5.87 lbs per HP?

Four strokes are getting as light or lighter than two stokes, Honda manufactures a line of tiny motors for lawn and garden that are just as light as two strokes, I powered a Dahon bicycle with one, and its way quieter, smoother, better idling than a two stroke.

[mikedefieslife]

Lol about the pollution posts considering most boaters will have diesel engine on the mothership pumping out much more/worse fumes.

[jamhass]

One more thought: 2 strokes are noisier than 4 strokes.

[mikedefieslife]

Originally Posted by jamhass

One more thought: 2 strokes are noisier than 4 strokes.

Some are for sure. My Mariner 2.5 is noisier than a Yam 2.5 4t, but The Yam 6hp 2T is quieter than a Honda 2.3 4T.

[Dockhead]

Originally Posted by valhalla360

You aren't the only one.

Only difference is it reminds me of snowmobiling. As a kid, dad would put me in front of him and my face was right up next to the carb.

I love the smell of two stroke exhaust in the morning! It smells like -- victory . . ..


Takes me back to being a 2 year old in a kapok life jacket on my father's dinghy, even all these decades later -- a rush of joy.

[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.