Yachting Monthly's oil-burning four-stroke?

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prv

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Page 7 of the "February" issue has a small piece on a new outboard. It's a four-stroke that aims to alleviate the which-way-to-lay-it-down problem by having a dry sump, ie storing its oil in a tank instead of the bottom of the engine. An intriguing idea. However, according to YM's finest, rather than being pumped around the engine and scavenged back to the tank, the oil in this four-stroke engine is:

...mixed with the petrol before passing to the carburettor.
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Shurely shome mishtake? :)

Pete
 
That is not right surely. I wonder if they mean a dry sump 4 stroke which is not a new idea. BSA (and others) motorbikes I am sure had dry sumps years ago and the oil was held in a tank in the side panel and pumped around. The oil was not burned as such it just circulated from the tank and back. Basically what PRV said!
 
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galadriel said:
Sounds like a 2 stroke! With the disadvantages of a 4 stroke!!
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It would be, if it was as described. Fortunately, I suspect journalistic cockup instead.

They also said that the conventional four-strokes that leak oil, do so through the air filter. I've never used a four-stroke outboard so am a little wary of calling them on it, but surely that can't be right either? Presumably it's some kind of crankcase breather that lets the oil out.

Pete
 
prv said:
It would be, if it was as described. Fortunately, I suspect journalistic cockup instead.

They also said that the conventional four-strokes that leak oil, do so through the air filter. I've never used a four-stroke outboard so am a little wary of calling them on it, but surely that can't be right either? Presumably it's some kind of crankcase breather that lets the oil out.

Pete
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That's because in line with all the modern emissions regs etc., the crankcase breathers go into the airbox so the "dirty" air from the crankcase is re-circulated again through the engine - so that is probably right I would think. Doing it this way avoids oil residues being either dripped out side or needing some sort of emptyable catcher. The Mariner I have (3.5hp 4S) can only be laid on one side, but my understanding is that small Yamaha's have a system already that allows the engine any side down - not sure if its a form of dry sump though - probably.
 
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They will have to pry my mariner 3.3 from my cold dead hands....
 
prv said:
It would be, if it was as described. Fortunately, I suspect journalistic cockup instead.

They also said that the conventional four-strokes that leak oil, do so through the air filter. I've never used a four-stroke outboard so am a little wary of calling them on it, but surely that can't be right either? Presumably it's some kind of crankcase breather that lets the oil out.

Pete
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Oil can find its way through the inlet valve, pass through the carburator and exit from the airfilter.
 
Ripster said:
That's because in line with all the modern emissions regs etc I would suspect, the crankcase breathers go into the airbox so the "dirty" air from the crankcase is re-circulated again through the engine - so that is probably right. Doing it this way avoids oil residues being either dripped out side or needing some sort of emptyable catcher.
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Fair enough. Just the new engine feeding the oil into the fuel supply, then :)

Pete
 
prv said:
Fair enough. Just the new engine feeding the oil into the fuel supply, then :)

Pete
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Yes, yes OK you got me..... :rolleyes: but the engine is not using the oil like a 2 stroke does. The amounts burned are miniscule if anything at all.
 
Reading what I could find this is most definitely a 4 stroke but uses the lubrication principle of a 2 stroke. It would seem that if it can do this and meet the emisions regulations then it is quite legal. The info I found clearly states that the oil used is 2 stroke oil. Interesting starting mechanism as well that takes about 3 easy pulls before setting it's self off.

http://www.bryggan.net/smi/pdf/selva/seahorse2-5.pdf

(second half is in english!)

Yoda
 
So you mix oil with the petrol, which would only lubricate the upper cylinders in a four stroke, so what then lubricates the lower engine? Presumably engine oil, but what keeps that in the crankcase allowing the engine to be laid down any which way? Unless there is no oil and the bearings are dry, sealed lubricated or kept alive by voodoo magic. Either that or it's dry sumped and they decided to burn some oil just for the heck of it.

Barring one of the above, or something similarly novel which hasn't occurred to me, I suspect it's a case of someone writing about something which they have no understanding of.

What's so hard about laying an engine down on a certain side anyway. There's only a choice of two sides. How taxing can it be to get it right?

Or does it draw the charge, oil and all, through the crankcase while still being a four stroke? If so, clever, but hasn't it been tried before?
 
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prv said:
Don't worry, my immaculate last-into-the-country Suzuki 2.2 is not going anywhere either. In fact I'm somewhat reluctant to take it out of the shed and put it on the boat :)

Pete
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I've a spare almost last into the country Tohatsu two-stroke sitting in the cellar for when the one in use (badged Mercury) finally gives up the ghost. Ran it for two hours to run it in a bit and check it, then flushed it, cleaned it and put some oil in the clynider before packing it away.

Tiny four-strokes are all big, heavy and no better for the environment than a very small two-stroke.
 
yoda said:
Reading what I could find this is most definitely a 4 stroke but uses the lubrication principle of a 2 stroke. It would seem that if it can do this and meet the emisions regulations then it is quite legal. The info I found clearly states that the oil used is 2 stroke oil. Interesting starting mechanism as well that takes about 3 easy pulls before setting it's self off.

http://www.bryggan.net/smi/pdf/selva/seahorse2-5.pdf

(second half is in english!)

Yoda
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Most novel; not unlike the oil injection used on larger two-stroke O/Bs. Watercooling the exhaust but not the cylinder head or block seems slightly perverse, but I guess it's shared with other equipment or something. Reasonably light too. Has anyone tried one?
 
Well, I have been buying my two-stroke oil from my mechanic, who sells it from a bulk drum. This reduces the cost somewhat, and also allows me to truly re-cycle the oil containers...
 
Personally, I don't see what the problem is. My 4 stroke has done probably tens of thousands of miles in the back of my car without ever spilling a drop of oil. Putting in down on one side only is no more complicated or inconvenient than bolting it onto the boat with the propeller in the water rather than in the air...:rolleyes:
 
prv said:
It would be, if it was as described. Fortunately, I suspect journalistic cockup instead.

They also said that the conventional four-strokes that leak oil, do so through the air filter. I've never used a four-stroke outboard so am a little wary of calling them on it, but surely that can't be right either? Presumably it's some kind of crankcase breather that lets the oil out.

Pete
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Its a crankcase breather on my Suzi, but I could see some putting the pipe in to the air filter as in older cars OR my MD22
Stu
 
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