2 Stroke vs 4 Stroke

[AliaVita]

I'm in Europe where 2 Strokes are not available due to high emissions. I'm aiming to buy a new rib and a 15/20hp outboard in the Caribbean as it will be tax free, so now also have the option of a 2 Stroke. My only knowledge of the pros and cons is that 2 strokes are lighter than 4 but you have to provide oil. Is there any more to it than that? Fuel consumption, reliability, noise, ease of starting etc.

Any advice would be gratefully received.

[Whaubner]

I'm sure others have a more exhaustive list of pros/cons


For years we had a 2 stroke 5 hp we have recently moved to a 20 hp 4 stroke. We made the switch primarily because our new sailboat has an 8 foot draft so we anchor a little further out these days.

The 4 stroke is awesome. It is easier to start, quiet, runs like a champ.

However...

1) it is heavy. ( takes two men and a boy to left). We have the dink with engine mounted on davits so this is not a big issue. If I was storing the engine separately on the rail I would go back to my little 5hp.

2) it is more complicated oil filter, fuel filter, zincs, ... The service kit has a lot more moving parts. Not terrible to do, but I feel the outboard has graduated to a full blown engine to maintain.

3) I worry my engine is now an attractive target for theft.

4) more expensive to buy initially

[sestina]

2 strokes are available in Europe. They are second hand. Brand new Tohatsu engines can be bought via the Channel Islands.

[robert sailor]

Tree huggers and weight lifters all prefer 4 strokes. They do burn less fuel. Me, I'll take a 15hp 2stroke Yamaha, bullet proof, easy and simple to work on, service parts anywhere in the world plus I'm bias I just like them due to my history with them.

[belizesailor]

Much discussion of this subject on other threads search for "Yamaha Enduro 15" will probably turn them up.

[Vasco]

For cruising I think a two stroke is the way to go. They are simple engines and will run forever with minimal maintenance. I just got a new one last year, a 15hp Yamaha. The tempting thing about four strokes is they burn a lot less fuel and there's no need to add 2 stroke oil but, in the final analysis, the two stroke's simplicity wins.

[tropicalescape]

2 strokes are very simple :suck, bang, boom.. no valves,weight to power ratio in favor of 2 strokes,if it wont start, can only be a few things wrong , trial and elimination will reduce problems faster than when dealing with a 4 stroke and they are very easy to rebuild when needed and the parts are cheap...Gotta love the smell of bean oil early in the mourning...

[SV Maclas]

I am a 2 stroke fan too. Weight being the big factor for me. A 15 HP motor is heavy, especially if you are trying to get it on and off the dinghy by yourself.

[Dockhead]

Plenty of discussion on this in the archives.

It's a matter of taste, of course, but personally I strongly prefer two strokes for dinghy propulsion.

They are much lighter, much simpler, have more torque and much better throttle response.

Those made in the last couple of decades (that is, with high energy electronic ignition) start extremely well and most of them (all of mine) are extremely reliable.

One very important advantage of two strokes for cruisers is that you can store them on their sides without the oil all leaking out or getting into the cylinder. This can be a major headache with four strokes.

The only downside of two strokes I know of is that they have worse fuel consumption.

For me, two strokes all the way. I'll be off to Guernsey if I ever need to replace my 12 year old 25 horsepower Mariner, but I don't know when that will ever be -- at this rate, it will outlast me. It's bulletproof.

[AliaVita]

Thanks for all your contributions, there seems to be quite a 2 stroke following on here! The motor will stay attached to the rib hanging from davits so weight is not important from a handling point of view, but my cat has expensive carbon bits to keep the weight down so is a factor from that point of view.

My only concern is that everyone says that they are easy to fix, but no one I have spoken to seems ever to need to fix a modern 4 stroke, and I don't want to have to fix anything! I have been referred to past threads which I am studying now. Jury is still out, but leaning towards a 2 stroke.

Thanks again, Rob

[colemj]

There is a very recent thread on this here.

A lot of people have opinions that were formed during the early days of small 4-stroke engines. While those opinions were valid then, they are not now - although they remain unexamined and dogmatically stuck.

The Yamaha 15hp Enduro 2-stroke weighs 89lbs. The Suzuki 20hp 4-stroke weighs 97lbs. So the total backbreaking difference between the two types is 8lbs (3.6kg). However, people stick to their beliefs on this point rather than the actual evidence.

A 4-stroke will have 35-45% better fuel economy. All of them come with a 3gal tank, which lasts for about 4hrs of continuous WOT running. To get the same range in a 2-stroke, they come with 6gal tanks. The extra 3gal adds 25lbs to the dinghy/engine package - which is much more weight than the difference between engines.

If you need to regularly lift your engine off the dinghy or carry it around, you should not be looking at 15hp of any type. The lightest 15hp of any type is still a chunk of weight to be lifting regularly.

It is in smaller engines where the 2-stroke weight advantage still holds true.

Our last 4-stroke engine was 15yrs old and had almost NO maintenance at all during those years. The carb was cleaned once, the oil changed twice, the plugs were replaced once and the water pump was replaced once (I do not recommend this abuse). The engine sat in the snow and freezing weather for 5 months each year for 5 years. It is still running strong on another boat.

If you regularly drop your engine in the water, or need to store it below decks at odd angles, then a 2-stroke is definitely better.

The torque differences between the two types disappeared a decade ago.

To call a person who prefers 4-strokes a "tree hugger" is ignorant. There are very valid advantages of them over 2-strokes.

Mark

[colemj]

Originally Posted by AliaVita

but my cat has expensive carbon bits to keep the weight down so is a factor from that point of view.

I assume you aren't talking about your pet, so what catamaran do you have? Your profile states a Bene...

Mark

[AliaVita]

Thanks for pointing that out, I'd better get updating. I am now (almost) the proud owner of a Catana 50. Just the other 90% to find! Deposit paid, survey done, sea trials next week. It's all quite exciting!

[Roy M]

Well put, colemj. A lot of folks don't tend to add up the hidden weight and hidden cost of all that wasted fuel.

[robert sailor]

Geez Mark, nothing wrong with being a tree huger, down side is they never hug you back! That aside choice is what makes the world go around and if you polled serious offshore cruisers you'd likely find almost all of them prefer 2 strokes. For local sailing where 2 strokes are no longer sold and good fuel economy you can't beat a 4 stroke.