2stroke or 4stroke

[bobhar]

can anyone tell me whats best 2 or 4stroke up to 20 hp many thanks bobhar

[beamishken]

I don't think you can beat 2 stroke for smaller portable engines there easier to carry, you can lay them any way you want and at that size the fuel consumption difference is negligible
No doubt many will disagree it's a bit like saying which is best tea or coffee

[Max...]

Yes, been done to death this one over the years. Apart from the newest small four strokes (in particular the latest Suzuki models becoming very popular which have negated many of the disadvantages) then the 9.8 Tohatsu, 15 hp Mercury/Mariner models etc are still the winners in terms of lightweight, portability, pick-up etc. The only disadvantages vs 4 stroke being noise and fuel consumption.

I've always been a 2 stroke fan but they are all getting older now of course and money no object then in all honesty a new Suzuki 20 4S would be my choice.

[paintman]

Have a read through this. Bear in mind you may not be able to buy a new 2-stroke unless you can prove you are a commercial user.
A two stroke or four stroke outboard engine ? | www.penninemarine.com

[Max...]

And I think a lot of that is aimed at larger RIB or hardboat users with 'fixed' and much higher HP installations rather than us lot with out little rubber tubs and piddly engines!

[Fenlander]

As Max says this issue has been chewed over across different forums for some years now.

Of course a major factor is are you comparing new motors (accepting there are grey new 2-strokes out there) or a new 4-stroke against a used 2-stroke?

The other important factor is if you are talking about a daily inflated SIB transported in the car boot... or one alwys on a trailer.

When I was first discussing this the last of the legal 2-strokes in the UK were barely 18mths old and the 4-strokes by and large more suited to a trailed and/or hard boats where their excessive weight wasn't a problem.

So back then for a non-trailed SIB and up to 20hp size it was 2-stroke every time for the portability aspect.

But since then each year the balance has been creeping towards the 4-strokes... to the point I swapped over to my current Suzuki DF20AS about 10mths ago from an excellent 2006 Mercury 15 2-stroke. A trigger for this was seeing they'd managed to get this Suzuki within 8kg of the Mercury weight for another 5hp. Also I was very keen on the Suzuki EFI system which I thought may just be less potentially troublesome than carbs might be with gumming and other isues seen now there is ethanol in the fuel.

The Suzuki 4-stroke is excellent but let's be realistic it's not life changing... just a load of small advantages that over time prove beneficial. I've come to appreciate the lower noise levels... particularly at and just above tickover trolling along wildlife areas in near silence. Not having to mix fuel is a small benefit but to me the larger one is being able to use spare fuel in the car to avoid storing a part tank for ages. I never minded 2-stroke smoke but it's nice not to have it or that occasional oily look to the water in a marina.

Fuel consumption monetary savings with a 20hp 4-stroke are not that much when SIBs are so cheap to run anyway... but a more important issue is the extra range allows me 50Nm on the same tank that did 32Nm with the 2-stroke. That is useful on longer cruises and negates my need to carry a second tank or can for backup.

EFI choke free starting is instant and you are never caught out with will it/won't it need choke. The EFI system also allows the mixture to be mapped far more accurately than a carb so the Suzuki can lean off in a constant cruise but deliver extra fuel when power is needed to give a 2-stroke like snap to the throttle.

Disadvantages are a little more care needed when lifting due to the extra weight. The upper and lower cowling is far more bulky than a 2-stroke which... added to the fact it can only be lay down on one side... makes it take up more space in the car. Servicing is expensive too if you've bought new and want to keep the warranty up... a timing belt that needs changing 4-yearly too.

Hope that helps whatever decision you are faced with.

[Merseyboy]

I made an enquiry about a new Suzuki 15hp 4 stroke to a large engine supplier who sells Suzuki and other brands. See his comments below about the Suzuki!

Regarding the engine, the Suzuki with it’s fuel injection system is proving somewhat troublesome and also we are getting lots of reports of corrosion problems. Consequently it is not an engine that we recommend. Of course it’s attraction is that it is light, but it appears Suzuki have cut a few too many corners to keep the weight down!

Anyone else have issues with this engine?
Cheers

[Fenlander]

Corrosion of what I wonder. EFI troublesome in what way? As someone who has invested cash in this still happy to read the negatives.

However... I spent around 20yrs in the motor trade and 've heard folks give strong opinion against buying pretty well every make of vehicle... some even would say avoid a Discovery! Dealer's bias was the worse of all and often related to profit margins, supply situation or an illogical but strongly held personal bias. So I just do a bit of open minded research, buy what I fancy and stand by that choice.

When I was asking about this Suzuki before I finally decided no-one had any ghastly tales to tell and a fellow forum member who owned one for had only praise. When he upgraded a few months back and sold it the condition at 3.5yrs old was mint and it had never missed a beat.

My personal view is that maintenance and overall care plus understanding a possible weakness is key for a long reliable life of any type of motor

[jeffstevens763@g]

I agree with the boys re 2/4 stroke I am on my 3rd Suzuki Df having had two Suzuki two strokes previously the old ones did suffer corrosion but so did mariner, Mercury, Johnson etc but paint and treatments have come a long way and the new Suzukis I have owned from 2008 have shown no corrosion never missed a beat and I am well impressed with them, I have had lots of expeariance running Yamaha, Mercury & tohatsu at work with no detrimental comments to make at all of any of them, but for me the DF is my choice.

[Max...]

I certainly would not base a buying decision on the comments of *one* dealer who probably has a very vested interest in promoting a certain brand. Do your research, listen to real owners on here (above) and scour the net for views. I have never owned a small 4S but did research the Suz a year or two back and could find nothing but praise.

[bobhar]

thanks for your quick reply i am new to boating have a quicksilver 430hd i will be buying 2nd hand engine around 1200£ what would you surgest thanks again bobhar

[beamishken]

In that case I'd say two stroke is your best option
Older 4 strokes are heavy and as has been said impeccable maintenance is essential, if you buy a poorly maintained one it could be a nightmare.
Two strokes will take years of neglect and keep plodding on due to their simplicity of design

[Fenlander]

Yes agreed one of the last of the 2-strokes will be ideal. I assume you are using a trailer with a 4.3m? If so a 20/25hp would be ideal and should easily come in budget.

I assume you are going to look privately on Ebay etc for an engine. If you have no experience of outboards take care to make sure you get a good one. There are plenty of great condition 2-stroke outboards about but a few dogs.

For your money before the season really gets going you should find a nice one as near to 2006 as possible with excellent cosmetics and a good sounding history from the seller who should be happy to demo in a tub of water. Tell the seller you'll want to see it started from cold (check it's cold by feeling under the cowl first and if they've pre-warmed it before you get there walk away) which it should do in 1-3 pulls. After a minute or two it should idle nicely with the choke returned. Check it pumps plenty of water from the tell tale. Look round the small details like shiny spark plugs free from rust... if someone can't be bothered to change those I'd worry about how it's been maintained.

Ask the seller what mixture it's been run on and ask to see the oil that's been used... hopefully you'll be shown a bottle of decent brand proper marine 2-stroke oil.

Bit like you would with a car... assess the seller as much as the outboard!

Here are a couple of examples of the type of condition I'd be looking for...

http://www.ebay.co.uk/itm/Yamaha-25h...IAAOSw4GVYR-hZ

http://www.ebay.co.uk/itm/Yamaha-25h...0AAOSw-0xYf8Uw

I prefer buying privately so would have been tempted by the second one... but I'd be factoring in its age which at 1996 is older than ideal but OK at the right price.

[Max...]

Yes, a 430HD is going to need a trailer and a 25 ideally. A big heavy lump even in a 2 stroke.

[jeffstevens763@g]

totally agree with the last three posts and with fenlander on the second engine looks tidy under the hood all the scuffs are to be expected with a portable engine the prop is sound and it looks like its had a lot of river use especially looking at the intake [mud stain].the 25 will give you good performance around 20 - 22knts at WOT depending on loading with the 430 from memory 120kg the gurnad runs one with a mariner 25hp he trails his boat too & packs in in his 4x4 i belive worth picking up on his threads for tips on use he's got it down to a fine art although his new toy is an Frib so you will have to go back a bit.

[JTURNER]

Hi, you cannot beat a small 2 stroke for power to weight. As it happens I have an old Auxilary of mine for sale. It was run just the once across the harbour in Dun Laouighaire (dublin) and then wrapped up nicely in storage. It is a Mercury 9.9hp has been fully serviced by the local agent last year (who are currently selling it on brokerage) and is effectively like new. If your interested PM me, the OB is in Ireland but I live in London so am over an back a bit. Best Jonathan

[bobhar]

thanks again its a great forum picked up a lot of info all ready i all ready have a trailer so just need engine .as their was no ours with the boat can any body rec amend a decent pair also a maitenace manual for the quicksilver many thanks again bobhar

[Fenlander]

bobhar have a look at this thread from The Gurnard who has the same SIB as you... might give some ideas...

http://www.rib.net/forum/f50/a-day-i...sib-62486.html

[T4Syncro]

Last year I bought a Quicksilver 430HD and 20HP Mariner 4 stroke both new in 2010. As said above its as much about the seller. I bought it because the seller had treated both like babies, very well maintained and apart from a few minor signs of use I'd have believed him if he said it had never been in the water.

What I'd like to add is that my 20HP 4 stroke mariner can plane with 5 up, that's me, my wife and our three daughters 11,17 & 18. Plus some gear. So a decent 20hp 4 stroke will get up and go. We have pulled a knee board happily with all but the more rotund gentleman.

That said, Last season I took the engine off after use and its a heavy lump. If like you I am buying separately I would probably choose a decent 2 stroke 25hp. It does sip fuel but I suspect a decent 2 stroke would too.

Hope that helps a bit.

[Gwozhog]

Yamaha 25hp 2stroke is What you need for your rig.