2 stroke vs 4 stroke

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ReggieK

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Gentlemen
As you were so helpful last time with my outboard problem, can I avail of your knowledge again.
Having decided to throw my Honda 5HP 4 stroke into the sea, because to repair the corrosion means obtaining parts ( 6 weeks delivery) There is no way I am stopping sailing for that period I have decided to purchase another engine. (No way a Honda)
I have been told that 2 stroke is a far better buy for an auxiliary.
Question: Is there a difference in power output between a 5hp 2 stroke and a 5 hp 4 stroke? I have no experience of 2 strokes.
 
Nope, the main difference is the smoke and the smell, the vastly different fuel consumption.

Suggest you buy a Yamaha with charging coil, 6hp I think, although the little Yam 4hp moved my Limbo 6.6 quite happily very economically.
 
I have seen quite a few etaps and the engine of choice appears to be the Yamaha 2 stroke twin 6 or 8 hp.
As to fuel consumption the 4 strokes on the whole use less fuel, but how much I cant say. PBO did a good test approx 18 months ago on a range of engines 5-10 hp, 2 and 4 stroke, well worth getting the article if you can.
THe last point is that You need to make sure you have the correct prop to drive a sail boat and not a fast planning tender! For me its a 2 stroke as they are significanltly less complex IMHO.
 
There is one small additional point !

2 stroke engines are no longer available new due to EU regulations so you will have to get a second hand one ( or old stock perhaps ? not sure if it's illegal to sell them or to manufacture them ? )
 
4 strokes tend to be much more efficient with a lower specific output (bigger engine for same power). 2 Strokes also consume oil along with the petrol, sometimes as a 'premix' where it's added to the petrol before getting to the engine, or as a separate tank on the engine. The oil can sometimes lead to a nasty exhaust, either as oily sludge spat out or as smoke.

2 Strokes are dead simple though, no valves, camshafts etc.

Regards

Richard.
 
[ QUOTE ]

There is one small additional point !

2 stroke engines are no longer available new due to EU regulations so you will have to get a second hand one ( or old stock perhaps ? not sure if it's illegal to sell them or to manufacture them ? )

[/ QUOTE ]

So long as they were imported prior to Jan 1st 2007 then they can be sold. A number of suppliers stockpiled a few, so I'm led to believe.
 
The 5HP Honda pushed my Etap no problem.
But now that I am forced to purchase a new engine and one dealer recommended 2 stroke was better as an auxiliary I thought I would tap the vast amount of knowledge on here.
This time I want to purchase the right engine, hence the questions.
I am drawn to Yamaha 5HP 2 stroke, but just wanted to be sure it would do the job.
I don't fancy all this fiddling about with oil business, but at the same time don't want to end up having to buy another new one in 3 years.
We can still get 2 stroke over here as they are still in stock.
Am I right in thinking that the Johnson is the same as Yamaha.
Can also get Mariner, but don't know much about them
 
Well, you're both sort of right and both sort of wrong. Two strokes have not been banned. Any engines which cannot meet new emissions limits have been banned. In effect strokers without fairly sophisticated engine management cannot meet the new levels, and to equip budget engines with it would make their cost untenable. So small strokers are in the process of becoming history in the EU.

Obviously, too, the stockpile of new strokers will dwindle over time and, although manufacturers have said they'll continue to stock spare parts for aeons to come...well, would you bet your boat on it?
 
For a tender I'd chose a 2-stroke every time: lighter for same power, cheaper, much more tolerant of being dropped in the drink.
For an auxillliary I wouldn't be so sure...depends partly on the sort of use you put it to. If you simply chug on and off a mooring or pontoon and then sail, a 2-stroke's shortcomings (thirstier, noisier, messier, ultimately less long-lived, at least in theory) are less relevant. But if you're likely to use it for an hour or more at a time, the balance swings towards a four stroke. I think some can also be rigged to charge your batteries, if that's an issue.

Most Mariners, incidentally, are made by Tohatsu.
 
I had a Honda 5HP and would have thrown it into the briny right behind yours, but sold it.
I got the Yamaha 4 stroke 4HP and it's been brilliant. Apart from having as much push as the Honda it uses less fuel and is quieter.
If you're going to leave it on the stern the slight weight disadvantage over a 2 stroke is irrelevant. The ability to use straight fuel, not as much of it, and not to leave a blue haze behind you is a distinct advantage.
 
2 strokes are great. they are easy to run and keep in good condition yourself and if you go for a decent 2 stroke there is no blue haze. having a 4 stroke on small bracket will have to be small (under 10hp) but a 2 stroke will be lighter so you can mount up to a 20hp. 2 strokes are very easy to start and are not as compact as 4 strokes so plug removal is much easier on a 2 stroke. My yamaha 4hp 4 stroke has the most difficult to remove spark plug i have ever seen.
 
Here here. I have Tohatsu 9.9 saildrive 2 stroke which just as you say doesn't smoke, is light and surprisingly quiet, and gives a charge of 13.2 volts at tickover with progressively more with revs. My engine sits in a well at the back of the cockpit but is light enough to lift off and lock away in the starboard cockpit locker, so its well protected from the elements as well as prying eyes - try doing that with a four stroke!

Also a couple of tips regarding oil mixing;

1 = get into the habit of always putting the oil into the tank (or petrol can) before the fuel , that way you won't forget about it between the garage forecourt and the boat.

2 = a 35mm plastic film canister is near enough exactly 40ml. So 2 of these filled with oil added to 4litres of unleaded will give a (fairly typical) 50:1 mix which is simple to do and without any mess.
 
What?
Why would anyone want to put a 20Hp on an Etap 21i?

The Yamaha plug is easily removed with a ring spanner. But I don't have to take it out very often. Unlike 2 strokes.
 
[ QUOTE ]
[ QUOTE ]

There is one small additional point !

2 stroke engines are no longer available new due to EU regulations so you will have to get a second hand one ( or old stock perhaps ? not sure if it's illegal to sell them or to manufacture them ? )

[/ QUOTE ]

So long as they were imported prior to Jan 1st 2007 then they can be sold. A number of suppliers stockpiled a few, so I'm led to believe.

[/ QUOTE ]

Wish I had ... I reckon anyone who sets up a s/hand outlet on 2st's - will make a bunce of dosh !! Unofficially of course !!
 
[ QUOTE ]
The 5HP Honda pushed my Etap no problem.
But now that I am forced to purchase a new engine and one dealer recommended 2 stroke was better as an auxiliary I thought I would tap the vast amount of knowledge on here.
This time I want to purchase the right engine, hence the questions.
I am drawn to Yamaha 5HP 2 stroke, but just wanted to be sure it would do the job.
I don't fancy all this fiddling about with oil business, but at the same time don't want to end up having to buy another new one in 3 years.
We can still get 2 stroke over here as they are still in stock.
Am I right in thinking that the Johnson is the same as Yamaha.
Can also get Mariner, but don't know much about them

[/ QUOTE ]

As an aux engine 2st is fine ... and simple as others say. Mixing the petrol / oil to me is a lot easier and better than remembering which way to lay a 4st down etc.

You say Yamaha ... Johnson is actually same as Evinrude NOT Yamaha. But many of the smaller engines around thye 2 - 3hp are based on the Tohatsu model.

Yamaha / Mercury / Mariner are very similar in many of the models and to be honest if Mariner is good enough for RNLI - it's good enough for me ...
In fact the best little engine I have is a Mariner 2.5 ... never seems to give up.

Sorry to say it - but there's a lot of rubbish spouted about outboards ... particularly this 2st vs 4st ..... I've seen more oil and mess spilt from 4st than a modern low oil mix 2st ... Plus the 2st is generally physically smaller and lighter in size.

For pushing a sailboat as an aux. - you can usually get the dealer to prop accordingly or get a "Sail" version that has a reduced gear ratio to get more thrust instead of out and out rpm ...
 
"(thirstier, noisier, messier, ultimately less long-lived, at least in theory)"

I would agree that most 2st are a little noisier ... and thirstier - but messier and less long-lived ? Sorry I do disagree there. AS I say in another post - I've seen more mess from 4st than a modern low oil ration 2st ..... second - I currently have a Johnson twin 4.5 that is serial # 1980 ... so that's 27 yrs old and only needed new throttle cable (actually one was made locally for 1/3rd price new ....), a new power head to leg gasket and a repair to water pump casing ......... total bill £50. That's not bad for 27 yrs ? The other olden is the Mariner 2.5 ... I bought s/hand for £120 8 yrs ago ... and only dealer job was to clear waterways about 4 yr ago ...

Simplicity ... wins everytime !
 
[ QUOTE ]
.......The Yamaha plug is easily removed with a ring spanner. But I don't have to take it out very often. Unlike 2 strokes.

[/ QUOTE ]

My 27 yr old Johnson .. which I've had for more than 10 yrs has never needed me to take the plug out ...
My 20 yr old Mariner 2.5 ... same story....
My 5 yr old Johnson 3.3 .... same story ....

Why do I need to pull a plug on a 2st more than a 4st ? Don't tell me ... Oiling up fouled plug ??? That means you have a problem with either start routine or engine fuel related problem ...
 
[ QUOTE ]
Why do I need to pull a plug on a 2st more than a 4st ? Don't tell me ... Oiling up fouled plug ??? That means you have a problem with either start routine or engine fuel related problem ...

[/ QUOTE ] Only echoing others concerns. I've never taken the plug out of my Seagull or Tohatsu either, but it takes all sorts.
 
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