4 or 2 stroke.

[Roadie]

I'm new to this forum and I am sure this has been asked before, but what do you all recommend. Currently I have an XPro 3.8m sib, with a 9.9hp mariner long shaft engine 4 stroke. Very nice engine but a long shaft, so looking at changing to a short shaft 15 or 20 hp next year, but should I steer away from 2 stroke and stick with 4.

[9D280]

Wlcome to Ribnet!

High level summary:

2- stroke = lighter weight to lug around
4- stroke = quieter, less smelly & if you do a lot of low speed stuff - more fuel efficient.

These of coures are big generalisations, and if you love the smell of a cold 2- stroke in the morning then it's a done deal!


Humour aside, one thing to watch is that the definition of "long" changes somewhere in the HP teens. I assume from your comment that you have found that out already, but thought it best you hear it twice than find your prop doesn't reach the water or you have an extra 5" draught that wasn't there before!


As to the "steer clear of 2- stroke" - This is a good polariser on theis forum, but unless you are on a trailer, all I'll say having had the dubious pleasure of lugging 28Kgs worth of 1972 Johnson 20Hp down to the beach (with 2 of us to carry it) that every Kg (or lack therof) helps! It may "only" be X kg, but outboards are remarkably awkward things to pick up. and if it's a 4- stroke will also likely be fussy as to how you can carry / lay it down.

[Peter_C]

Owning a two stroke, and having played in a four stroke yesterday that was a 9.9hp I am all for the cleaning running 4 strokes.

[CelticNate]

Wow... Is my engine too big then? Got a 3.8m rib with a tohatsu 30hp 2 stroke on it...

[Amcarrapatoso]

I had a 3.5 m RIB with a 25 HP 2 ST Mariner. Very fast and fun to ride. Light and not so hungry on fuel.
I moved to a larger RIB (4.5 m RIB with a 40 HP 2 ST Mariner). Not so fast but still fun to ride. Heavier and hungrier.
Now I own a larger RIB (5.2 m RIB with a 90 HP 4 ST Suzuki). Faster than the previous ones and fun to ride but much heavier and needing less fuel.
Just a final comment: since I normally use the RIB in a lake, the usage of a 4 ST is almost a must.

[lockieboi]

Originally Posted by Roadie

I'm new to this forum and I am sure this has been asked before, but what do you all recommend. Currently I have an XPro 3.8m sib, with a 9.9hp mariner long shaft engine 4 stroke. Very nice engine but a long shaft, so looking at changing to a short shaft 15 or 20 hp next year, but should I steer away from 2 stroke and stick with 4.

The weight is the deciding factor for us SIBers.
I assemble and dissemble my SIB everytime and have used a 15hp 2 stroke and now have a 25hp 2 stroke. The 15 weighs about 36kgs and the 25 about 50.
If you're looking at getting a 15hp 4 stroke I think they weigh roughly the same as my 25!
So for no extra weight you get 10 more horses.
Long live the 2 smoke!
Obviously if your trailering then my input is irrelevant.

[Roadie]

My 9.9 weighs 50 kg, so is just about manageable on my own as I too assemble each time.

[Projectile]

New or used?

If you're in the market for a new engine, get a new ETEC 2- stroke. I love my ETEC 30: quiet, no smoke, no smell, powerful, clean, efficient, lovely. Very little maintenance too, and no break-in required.

If you're in the market for an older engine, then, unfortunately, the older 2-strokes don't come close to the new ETECs. I'd get an older 4-stroke if the weight was ok.

[azzurro]

I understand that banning small 2strokes is stupid (they may be dirty but because of being small they are not so much as big ones); and small engines need to be as light as possible (personally I do not care about a 50hp engine being heavier since I will not move with my arms) so I think small 2 strokes should be allowed.

But when 2stroke vs. 4stroke evaluating, consider this:

1.- 2 strokes are banned in inner waters in most european countries.
Also in most european countries you will not be able to register a old 2stroke in a new boat (in Spain, since 2010). Thus you will not be able to get assurance, etc. So you will be ot of the law.
However boats older than 2010 can still use their old 2 stroke engines (but cannot replace them with other 2 strokes).

I do not know UK and USA laws but I believe they might be getting the same restrictions. Also, I do not now whether in UK and USA illegal boat owners are allowed because of relaxed law culture. Here in Spain, if you are lucky enough you may never get one, but...
boat bills have three zeros!

2.- 2 strokes are getting older since they are no longer manufactured. As a result of this and because of the demand, second hand 2 strokes are getting too much expensive.



On any other discussion such as maintenance, toughness, weight, etc. I think small 2 strokes are far better than small 4 strokes (yes, 4 stroke may be more fuel saving engines, but we are talking about small engines!).

[Pikey Dave]

Originally Posted by azzurro

1.- 2 strokes are banned in inner waters in most european countries.
2.- 2 strokes are getting older since they are no longer manufactured.

Hmmm, not so sure about that

[azzurro]

Originally Posted by Pikey Dave

Hmmm, not so sure about that

You are right, Evinrude E-tec are not banned. They are the only one manufacturer which is not banned because of low emmissions.

But E-Tec small outboards (i.e. 15hp) do not have any advantage vs. 4 strokes.
- Much heavier than 4strokes (!!!!!)
- Not as tough as old 2strokes.

OK, you may lay them in the floor on both sides. But quoting E-Tec engines in this thread is absurd.

[Pikey Dave]

Just to clarify

Originally Posted by azzurro

You are right, Evinrude E-tec are not banned. They are the only one manufacturer which is not banned because of low emmissions. I'm glad we cleared that up then

But E-Tec small outboards (i.e. 15hp) do not have any advantage vs. 4 strokes.Smallest Etec is actually 25hp so is probably just outside the scope of this discussion
- Much heavier than 4strokes (!!!!!) Eh! The lightest 25hp Etec is 66kg, the lightest 4s Yammy is 76KG
- Not as tough as old 2strokes. Says who, I'll fight you for it

OK, you may lay them in the floor on both sides. But quoting E-Tec engines in this thread is absurd Absurd is a bit strong, slightly irrelevant maybe, but so is saying that 2strokes are banned on inland waters & production has ceased. .

We wouldn't want to cause any confusion, would we?

[lockieboi]

Originally Posted by Roadie

My 9.9 weighs 50 kg, so is just about manageable on my own as I too assemble each time.

So get yourself a nice 25hp 2 stroke and you'll be handling the same weight but have an extra 15hp to play with.

[sparky666]

my mariner 20 4 stroke only weighs 50kg not much more than a two stroke,its quiet,no expensive two stroke oil,consumes less fuel than an equivalent two stroke,and burns clean.
Dare i say four strokes are less complicated than a modern injected two stroke
servicing a four stroke has a few additional items,oil and filter and a new easily changed cam belt every three or four years with the addition of valve clearance adjustments if ever needed.
this is easy to do and parts can be obtained cheaply.
But overall cruising up a river quietly with no smoke wins it every time for me

[simsy]

I loved the lower weight and power (torque in midrange) and simplicity of my previous 2 smokes.... Great for racing....

But the noise after a while!!!! My 4 stroke is so smooth and quiet.....

For performance all round, stick to 2 stroke.. for refinement buy 4 stroke...

we are talking about small outboards, not large modern air scavenging 2 strokes

[sparky666]

perfectly put, a four stroke is a day in day out allrounder

[clydeoutboards]

and the honda 20hp short shaft is only 47kg.

they also attended the UK's largest boat show as did suzi, yamaha, mercury/ mariner, Tohatsu etc but amazingly Evinrude were the only manufacture that didnt and have a UK office for marine staff like most other manufactures apart from Evinrude!

back to OP question. 2 stroke if you are looking for max power to weight ratio and have a limited budget as they are cheaper 2nd hand than 4 strokes. yes they are older but they also dont cost silly money 2nd hand.

[chipko]

Love the idea of 2 stroke power to weight ratio but preferred the benefits to buy a new, so channelled down the 4 stroke route. Finally decided on a Suzuki DF20A short shaft, fuel injected, at 44kg not a massive weight penalty over 2 strokes, and just manageable to lug around single handed - boat left inflated but engine removed after use. Early days but not regretting it so far - quiet, powerful, economical and under warranty.

[sparky666]

That is a light engine and fuel injected ,good one!

[frankc]

Check out this video. They compare 15 HP Yamahas.

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