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South devon Report 2009
- Thread starter scottwilson
- Start date
Thread Status: Hello
, There was no answer in this thread for more than 90 days.
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The only reasons to choose 2 stroke that I can see are purchase cost and weight.
4 strokes are heavier which doesn't matter much provided you leave the motor on the boat and have easy launch sites but on steep beaches I was always very glad of my air floor boat and 2 stroke motor.
Cost wise a 2 stroke will be certainly be cheaper to buy but with fuel prices as they are a 4 stroke will probably soon pay for itself in considerably reduced fuel bills.
4 strokes are heavier which doesn't matter much provided you leave the motor on the boat and have easy launch sites but on steep beaches I was always very glad of my air floor boat and 2 stroke motor.
Cost wise a 2 stroke will be certainly be cheaper to buy but with fuel prices as they are a 4 stroke will probably soon pay for itself in considerably reduced fuel bills.
Hmmm. interesting discussion and one that seems to come along every so often in various places: 2 stroke or 4 stroke... for what its worth i went down the 2 stroke route on our Mariner 90 Optimax and i think its superb - (it mixes the oil itself so no bother there..). Does the engine auto-mix on a smaller engine? Might be worth checking what the actual weight difference is between 2 and 4 str.
Also, servicing - presumably the 2str is cheaper/easier to service or even self-sevice?
CW009 - do you actually flush your engine
didnt think people did that any more... 
(just kidding as i've never seen anyone doing that over here so i started asking people about it when we bought our boat, consensus was that no one bothers!)
One more thing Gaz, make sure get get a kill chord and dont go out without it in place! sorry if that seems obvious, worth re-iterating.
Also, servicing - presumably the 2str is cheaper/easier to service or even self-sevice?
CW009 - do you actually flush your engine
didnt think people did that any more... (just kidding as i've never seen anyone doing that over here so i started asking people about it when we bought our boat, consensus was that no one bothers!)One more thing Gaz, make sure get get a kill chord and dont go out without it in place! sorry if that seems obvious, worth re-iterating.
Small 2 strokes don't auto mix. In fact small 2 strokes are completely different from big 2 strokes. Big 2 strokes with fuel injection and such like are lean clean machines with performance to match 4 strokes. Consequently their manufacture has not been banned as has happened with small 2 strokes that are incapable of meeting current emission regulations.
For what its worth I have a 50Hp Mariner (2004) on a 4.2m Rib - its the max as per the rating. Goes very quick. But is very thirsty and noisy compared to fourstroke.
It automixes fuel and oil.
It is simple to do basic service right down to impellor change.
The main issue I have with it is that it takes a while to start, but once running its as sweet as a nut. The starting problems are likely to be down to my own technique...
It automixes fuel and oil.
It is simple to do basic service right down to impellor change.
The main issue I have with it is that it takes a while to start, but once running its as sweet as a nut. The starting problems are likely to be down to my own technique...
Legal to own and use small 2 strokes, just not legal to manufacture them any more (since 2006) so a time will come when we won't be having this discussion as there won't be many good 2 strokes left to buy.
i have the same bombard with a 15 two stroke,
With two up and all spearo kit it's perfect, will do about 20 knts!
Put three in it and getting on the plane can be difficult but once it's up it still goes fine!
The engine does its own oil mixing!!
i regularly take it from Portsmouth to the isle of Wight without any worries, the engine weighs very little and uses hardly any fuel!
With two up and all spearo kit it's perfect, will do about 20 knts!
Put three in it and getting on the plane can be difficult but once it's up it still goes fine!
The engine does its own oil mixing!!
i regularly take it from Portsmouth to the isle of Wight without any worries, the engine weighs very little and uses hardly any fuel!
Lots of confusion!
This is my take on the discussion - automixing is not quite the issue with two strokes as this has been around for decades it is the clean burn fuel injection models that are still being produced.
Carburetter two stroke are unable to meet modern admission regulations but fuel injected two strokes easily make the grade.
However I think at present the smallest fuel injected two stroke is 40hp.
You can always find some debate as to which is best - injected 2S or FS (either carb or injected four stroke) The truth is fuel economy is pretty much the same however injected two strokes sound fantastic & FSs sound tame in comparison!
As far as weight goes you wont find much difference in that either - Honda have always produced lightweight FS engines.
This is my take on the discussion - automixing is not quite the issue with two strokes as this has been around for decades it is the clean burn fuel injection models that are still being produced.
Carburetter two stroke are unable to meet modern admission regulations but fuel injected two strokes easily make the grade.
However I think at present the smallest fuel injected two stroke is 40hp.
You can always find some debate as to which is best - injected 2S or FS (either carb or injected four stroke) The truth is fuel economy is pretty much the same however injected two strokes sound fantastic & FSs sound tame in comparison!
As far as weight goes you wont find much difference in that either - Honda have always produced lightweight FS engines.
On my old inflatable I had a 40hp 2 stroke and it was almost to much engine, even though the boat was capable of taking it.
On my current rib I’ve got a Honda 90hp four stroke and it’s a lovely engine, but it is on a much bigger boat.
On the small inflatable I’d still go with the 2 stroke mad revving nutter engine, as they are more fun on a light boat.
On my current rib I’ve got a Honda 90hp four stroke and it’s a lovely engine, but it is on a much bigger boat.
On the small inflatable I’d still go with the 2 stroke mad revving nutter engine, as they are more fun on a light boat.
If You get the 4stroke will be smilling when you shake your fuel can after a long day out diving, i dont think you will doing that if you go for the 2 stroke. And you will be happy you can hear youself thinking with the 4stroke. I think 2 strokes will slowly die out, 4 stroke is better in every way.
Nice inflatable Gaz!!! is it on a trailer or launch wheels?
My zodiac 3.8 has launch wheels and a 15hp and I can just about pull it up a slipway with all my gear in it. I was thinking about going for a bigger engine but the jump in weight from a 15 to a 25 is big. My old 15hp motors me along nicely and like Spearheads, majority of my boat dives are on my own.
My zodiac 3.8 has launch wheels and a 15hp and I can just about pull it up a slipway with all my gear in it. I was thinking about going for a bigger engine but the jump in weight from a 15 to a 25 is big. My old 15hp motors me along nicely and like Spearheads, majority of my boat dives are on my own.
CW009 - do you actually flush your engine didnt think people did that any more... (just kidding as i've never seen anyone doing that over here so i started asking people about it when we bought our boat, consensus was that no one bothers!)
Always,always do it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Fool not too. You wouldn't sh** in your WC and not flush it would you?
Tribs
didnt think people did that any more... (just kidding as i've never seen anyone doing that over here so i started asking people about it when we bought our boat, consensus was that no one bothers!)Always,always do it!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! Fool not too. You wouldn't sh** in your WC and not flush it would you?
Tribs
erm... no...
but if i had an inboard 90 rather than an outboard 90 i wouldnt have the option to flush it.
It's got those removable launch wheels mate, and I intend to ferry the boat around upside down on my roofrack (that is untried at the moment, but the Bombard Aerotec is a really light boat, apparently - which was one of the main considerations behind buying it). I don't want to get involved with trailers, not at this stage anyway.
I'll probably end up going with the 15hp 2 stroke, again for weight reasons, as I've got this (probably mad) idea that I will be able to launch it from virtually anywhere, if I can just manhandle it down to the water (maybe on my own, in two shifts, but I certainly don't see that as a problem if there is two people).
My only real concern with a 15 hp engine is that the Bombard has quite large tubes, so might need a bit of extra 'push' - but Speardaver's post has put my mind to rest on that. So I'll probably go with the 15hp 2 stroke if I can get one, and work upwards from there if I'm not happy.
Therefore . . .
. . . has anyone out there got a 15hp 2 stroke for sale?
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Things change all the time & it is difficult to keep up to speed but most (some) new motors have a 1/2'' barb to attach a fresh water hose to.
If you keep your boat on a pontoon mooring like I do you simply attach the marina fresh water supply to the engine for a few seconds to flush out any sea water.
I guesse it is just as easy if you have your boat on a trailer to do the same at home.
However if like James your motor does not have this facility then you could attach some ears as James said. These ears look like a set of studio headphones & just self clamp onto the outboard water intake.
If you keep your boat on a pontoon mooring like I do you simply attach the marina fresh water supply to the engine for a few seconds to flush out any sea water.
I guesse it is just as easy if you have your boat on a trailer to do the same at home.
However if like James your motor does not have this facility then you could attach some ears as James said. These ears look like a set of studio headphones & just self clamp onto the outboard water intake.
I can look into it mate, regarding the quote, but it's really just me repeating what I've been told by the people who sell and maintain second hand engines. General rule: 2 strokes are lighter and have got more umph.
If that isn't actually the case then I would be delighted, as it seems that 2 strokes are not as easy to get your hands on as 4 strokes (especially when you are talking around 25hp mark, as so many people want to go with the lighter engine, apparently).
But you are right, I shouldn't just take their word for it, but should do my research more thoroughly and look into the specific weights differences a bit more - because if the differences are negligable I won't have to narrow my seach so much.
Gaz, your contacts are right to a certain extent but it is not always so clear cut - from memory I think Mariner 15hp & Yam 15 hp are about 80 -85lb in there two stroke forms but the 20hp mods are around 110lb.
Tohatsu & Honda 15hp 4s are definitely heavier at around 100lb but there 20hp models are the same engine & therefore weigh less than the 20hp two strokes!
The big issue in my mind is that small carb 2s dont like to idle (tick-over) for long & tend to oil up plugs.
Tohatsu & Honda 15hp 4s are definitely heavier at around 100lb but there 20hp models are the same engine & therefore weigh less than the 20hp two strokes!
The big issue in my mind is that small carb 2s dont like to idle (tick-over) for long & tend to oil up plugs.