Myths around 4 stokes

steve66 said:
I have a 4 stroke thats as light as a 2 stroke!!! and i dont care how advanced engineering has become 100/1 is suicidal in a 2 stroke
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Is 100:1 any more suicidal than a 4 stroke with no oil pump?
I can decide to run the Yam with 50% extra oil of course.
Let us know how your outboard is going in 20 years' time, when I expect my Yamaha to be past it.
4 strokes are great from about 10hp upwards when fuel economy starts to matter.
But whether it works is more to do with an engine's history than whether it's a 2 or 4 stroke.
 
If I'm a luddite how come my Mariner 5hp 2 stroke engine running at 100:1 is as good as new and has motorsailed my boat across the Channel a fair few times ( 4 I think off the top of my head could be more ) and around the Solent etc ?

As for Kent engines that really is Luddite territory, I had a Capri ! They can take their designed solely for ease of manufacture Heron Head and...

Jumbleduck,

I'd be genuinely interested to hear what's involved in running a Seagull on bio fuel ?

I don't have a Seagull though, around here they're quaint nick knacks for the walls in waterside pubs, though it has to be said I was introduced to cruiser sailing using these things and a pub wall seems a jolly good place unless you've discovered the Holy Grail !

My Dad does have an ancient British Anzani he was given which he attacks every now & then, more of a challenge than a project...
 
lw395 said:
Is 100:1 any more suicidal than a 4 stroke with no oil pump?
I can decide to run the Yam with 50% extra oil of course.
Let us know how your outboard is going in 20 years' time, when I expect my Yamaha to be past it.
4 strokes are great from about 10hp upwards when fuel economy starts to matter.
But whether it works is more to do with an engine's history than whether it's a 2 or 4 stroke.
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Ok here we go....... i have a 2hp honda 1991 still singing like a sewing machine and have bought and sold many more like it. Your absolutely correct small 4 strokes dont have oil pumps, they have oil slingers that if you have oil in the sump work perfectly well. You have a look at the jet size on your 2 stroke and i will bet my house its far larger than an equivalent 2 stroke so a 4 stroke whatever the hp will be far more efficient. Whatever outboard you have whether its a 1965 40 plus or a 2013 3.5 mercury it owes its reliability to good maintenance
 
Seajet said:
I'd be genuinely interested to hear what's involved in running a Seagull on bio fuel ?
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It's a while since I've done it, but the general idea was (a) mix petrol and biodegradable two-stroke oil (b) put in tank of Seagull (c) start Seagull (d) clatter off in clouds of smoke and smugness. Biodegradable two stroke oil has been around for ages - I first bought some from the filling station at Auchenlochan Pier Head twenty years ago - and is currently available from, among others, Castrol, as Biolube 2T.

Somewhere in the attic I have a British Anzani; the wee one with an elliptical tank around the Seagull-style exposed flywheel. I doubt that I'll ever get around to restoring it, so if anyone wants it, PM me with a modest offer.
 
I think you mean ' scavenge ' oil pick up systems in sumps.

Have a look at the weight of the 4 stroke 2-3hp range tender engines now available compared to the sensible 2hp 2-stroke Mariner / Yamaha / Suzuki engines which one could actually lift safely on and off a cruiser, including SWMBO doing it on the odd occasion it might and will be required; 4 strokes for this purpose are a bad and dangerous joke.
 
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Seajet said:
As for Kent engines that really is Luddite territory, I had a Capri ! They can take their designed solely for ease of manufacture Heron Head and...
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Oh dear.
I don't have a Kent engine. I asked about it to glean some experience on Weber carbs.
My motor is a Suzuki. Suzuki, you know, the company who have never built an engine that didn't have an overhead camshaft.
 
No Seajet i mean an oil slinger either a 3 legged wheel that runs off the crankshaft in the case of Tohatsu based motors or as fitted to hondas small wheels with spokes that also run off the crank that sling oil all around the crankcase of the engines.The weight of a 2 hp Honda 4 stroke is 12 kgs. You ought to try one one day!!!!
Seajet said:
I think you mean ' scavenge ' oil pick up systems in sumps.

Have a look at the weight of the 4 stroke 2-3hp range tender engines now available compared to the sensible 2hp 2-stroke Mariner / Yamaha / Suzuki engines which one could actually lift safely on and off a cruiser, including SWMBO doing it on the odd occasion it might and will be required; 4 strokes for this purpose are a bad and dangerous joke.
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Well as far as I remember re motorbikes and overhead cams I think Honda started it and Kawasaki refined it, I've had immediately later versions of both; my last bike before I found the increased aggressive traffic here made it unenjoyable and downright dangerous was a Suzuki GSX750ESD, one of the first of the rear monoshock smaller front wheel jobs.

Kent engines were the creation of the devil, but to get back to boats Lombardini air cooled dumper truck engines were many times worse; I knew a boat where a prat had installed one of these things, one could not walk on the grp cockpit sole in bare feet, it was too hot !
 
And this is where i surrender to this thread!!!!!. I really dont think you have ever picked up a 2 hp honda , if you have and you think they are heavy i suggest a trip to the doctors. A sump scavenger is usually a driven pump used in dry sump racing engines.
If anyone else thinks im incorrect please say and i will give up engineering and take up flower arranging!!!!
Seajet said:
steve66,

what you describe is what I and others call a sump scavenge; and I've tried the 4 stroke 2hp jobs, very heavy...
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A scavenge system may be a pump or simply collecting oil from the sump on cam like devices and dumping it over the top !

I did say let's go to the lounge as this doesn't seem nautical in the context presented; if I don't see you there let's finish this now.
 
Lakesailor said:
Oh dear.
I don't have a Kent engine. I asked about it to glean some experience on Weber carbs.
My motor is a Suzuki. Suzuki, you know, the company who have never built an engine that didn't have an overhead camshaft.
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Not quite exactly.
Suzuki were mostly two strokes when I were young.
Well the small ones anyway.
 
Seajet said:
Well as far as I remember re motorbikes and overhead cams I think Honda started it and Kawasaki refined it
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Peugeot were the first to make a success of it, almost exactly 100 years ago, with a dohc 600cc straight four. What Honda did (along with Cosworth) was develop the four-valve pent-roof head in the Sixties, although it was a while before this layout appeared on their road bikes, most being 2-valve sohc. There were plenty of ohc road bikes between Peugeot and Honda, although ohv was of course much more common. Kawasaki were johnny-come-latelies who started off making copies of ohv British twins before developing a two-stroke range, then the dohc 2-valve Z1 and its successors. As for 'refining'...I think everyone did that.
 
Seajet said:
Have a look at the weight of the 4 stroke 2-3hp range tender engines now available compared to the sensible 2hp 2-stroke Mariner / Yamaha / Suzuki engines which one could actually lift safely on and off a cruiser, including SWMBO doing it on the odd occasion it might and will be required; 4 strokes for this purpose are a bad and dangerous joke.
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This point is my criterion for an outboard - well, reliability too, of course, which includes easy starting. As a 78-year old, single-hander, getting the damned thing hoisted from inflatable to pushpit bracket in a bouncy anchorage can be a problem; every kilo shaved off is a bonus for me.

Because of the challenge, last year just the one time I neglected my golden rule to never leave the engine on the dinghy overnight. A 45 knot wind blew up at midnight (in true Murphy effect) and I was a full hour fighting an inverted dinghy and retrieving a submerged Johnson 3.5hp, 2-stroke. It started next morning after cleaning and drying and has run perfectly since... Would a 4-stroke have done the same? I dunno, just asking.
 
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Check the big end when you get the chance, but yes my Mariner 2hp 2 stroke tender engine has been inverted and submerged in salt water 4 times since I bought it in 1987, thanks to the ineptitude of myself and others.

It has got away with fresh water flushes and one set of main bearings and still delivers, I hate to say it about a Japanese product and wish there was a British alternative, but it's a brilliant engine, I know a friends' Yamaha 4hp 2 stroke has gone through a similar career and is the same, still a good 'un.
 
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