Myths around 4 stokes

dunedin said:
Why should a 4 stroke be more reliable than a 2 stroke ? What engineering basis is there for that hypothesis
Click to expand...

It's largely a long-term (high mileage) phenomenon, and as such would have less bearing on 95% of small outboards than the quality of care they received. Conventional four-stroke bottom ends fare better with their positive lubrication; two stroke crank seals eventually wear out; two-stroke piston rings suffer higher wear through whizzing across holes in the cylinder (which is more a power than reliability effect). If you wanted a 200,000mile car engine, you probably wouldn't want it to be a two-stroke. And high-performance two-strokes (which does not include small outboards) are definitely more prone to holing pistons. (If you're lucky: if you're not, you just take off the exhaust and shake out corn-flake-sized chunks of piston :D. Been there. done that.)

And yet, Ford, Mercedes and several others quite recently spent $billions trying to develop direct-injection 2-stroke engines for cars. Mind you, they would have had bottom-ends more like four-strokes.

That said, stinkwheels' reliability reputation arose as much from plug fouling as anything else, a factor very much reduced by better ignitions, spark plugs and two-stroke oils.
 
macd said:
It's largely a long-term (high mileage) phenomenon
Click to expand...

The question is how many outboards die through over use rather than lack of use... OK Commercial are different but us amateurs outboards normally die through lack of use and expensive parts that have fixxed away...

I cannot see 4 stroke engines changing that?
 
Well my 15 hp 2 stroke Johnson was still starting easily and doing the business despite being 27 years old when it got stolen.

Why was it stolen well it seems well know that they just keep ticking. A brand new unsecured Honda 4 stroke was ignored and they cut the security lanyard to steal my old Johnson.

It got replaced with another 2 stroke. As far as I can see the only 2 benefit are lower noise and emissions if buying a 4 stroke.
 
My comment about Honda was induced by an experience a couple of days ago when I could hear my friend approaching from a mile away. Actually, I quite like my Suzuki 2.5. Although a bit heavier, it has much more poke than my old 2.2 and I don't have the bother of mixing up fuel/oil. Because of the laying-down problem it usually lives on the pushpit, which is convenient but not very elegant.
 
onesea said:
The question is how many outboards die through over use rather than lack of use... OK Commercial are different but us amateurs outboards normally die through lack of use and expensive parts that have fixxed away...
Click to expand...

Precisely why I qualified my observation with "It's largely a long-term (high mileage) phenomenon, and as such would have less bearing on 95% of small outboards than the quality of care they received."
 
macd said:
Precisely why I qualified my observation with "It's largely a long-term (high mileage) phenomenon, and as such would have less bearing on 95% of small outboards than the quality of care they received."
Click to expand...

Thanks for your explanation, very helpful. Our outboard lies idle for perhaps 355 days a year, and runs for 15 minutes or so on the other 10, so "high mileage" issues should be a long way off. It's avoiding seizing over he winter that is the real challenge
 
stu9000 said:
It was a crime not to exempt 2 strokes from the legislation. It was lobbied hard but to no avail.
Click to expand...

I'm not sure the legislation even mentions 2-strokes (or 4-strokes); there's no particular reason it should. As noted above, 2-strokes aren't banned per se, so much as unable in basic form to meet emissions limits. It may have been that those lobbying hoped to exempt small engines in general.
 
stu9000 said:
It was a crime not to exempt 2 strokes from the legislation. It was lobbied hard but to no avail.
Click to expand...

But its amazing that both Amazon UK and Ebay UK are advertising and selling small Chinese 2 stroke outboards, and some adverts even say "shipped from UK": http://www.amazon.co.uk/Sanven-Stro...d=1379243780&sr=1-12&keywords=outboard+engine.

Obviously some people are just ignoring the regs. Not that I am tempted to buy one - unknown Chinese makes strikes me as a bad buy, even at the cheap-ish prices. I am not really against people ignoring a stupid nonsense EC regulation. Just wish they would advertise a new Tohatsu 3.5 instead of a hangchengwatsit.
 
dartmoor said:
But its amazing that both Amazon UK and Ebay UK are advertising and selling small Chinese 2 stroke outboards, and some adverts even say "shipped from UK": http://www.amazon.co.uk/Sanven-Stro...d=1379243780&sr=1-12&keywords=outboard+engine.

Obviously some people are just ignoring the regs. Not that I am tempted to buy one - unknown Chinese makes strikes me as a bad buy, even at the cheap-ish prices. I am not really against people ignoring a stupid nonsense EC regulation. Just wish they would advertise a new Tohatsu 3.5 instead of a hangchengwatsit.
Click to expand...

The two stroke advertised in Amazon is a good price but the ration fuel/oil is 20~25:1; I wander is anyone form this forum has bought this outboard.
 
CAPTAIN FANTASTIC said:
The two stroke advertised in Amazon is a good price but the ration fuel/oil is 20~25:1; I wander is anyone form this forum has bought this outboard.
Click to expand...

Not me I'm afraid. I am a +++1 fan for two strokes but not at 20/1, 100/1 yes. We spend 8 months a year at anchor and the tender with a Tohatsu 3.5 leaves the boat at least twice a day, it starts day or night first pull (generally without choke). If anyone is having trouble in our 8 months of visiting anchorages with starting or keeping running when it's engaged drive, it's a four stroke every time! To sum up for me, A,B,C is a myth and who really cares about D, a few sheckles a season!!
 
dartmoor said:
But its amazing that both Amazon UK and Ebay UK are advertising and selling small Chinese 2 stroke outboards, and some adverts even say "shipped from UK": http://www.amazon.co.uk/Sanven-Stro...d=1379243780&sr=1-12&keywords=outboard+engine.

Obviously some people are just ignoring the regs. Not that I am tempted to buy one - unknown Chinese makes strikes me as a bad buy, even at the cheap-ish prices. I am not really against people ignoring a stupid nonsense EC regulation. Just wish they would advertise a new Tohatsu 3.5 instead of a hangchengwatsit.
Click to expand...

Be warned, they aren't just ignoring the regs, they may well be drop-shipping from China which is completely illegal. I'll try to find the thread, but a few forumites looked into this a while ago - try sending Mr Ebay a message, you'll get something in fractured english in response telling you how they don't have anything in the UK warehouse right now, but if you place the order, the new stock will arrive in a few weeks...and try at great pains to reference "our UK warehouse" as much as possible...

EDIT: Just clicked your Amazon link - same guys as the ones we looked at way back then!!!- try finding out who the seller is : "Shangwen Industrial Co. Ltd" - Shipping from Portsmouth, UK...Aye Right!! (Hint : Companies house don't have a Shangwen Industrial Co registered!) - Any problems with that engine and your warranty will be worth the electronic page it's typed into... ;)

If you really want to, 2-strokes can still be purchased through Jersey in the Channel Islands via retail, if rumours are true.
 
Last edited:
L for Light applying to 2 strokes

H for Hernia applying to 4 strokes

E applies to 2 strokes pretty well now with late 20th Century designs running at 100:1, we aren't using Seagull engines and speaking trumpets for hearing aids...:rolleyes:
 
You must log in or register to reply here.

Share this page

Top