2 strokes illegal in US????

[Sailmonkey]

Originally Posted by Jim Cate

I find that hard to believe, having had great long lives from various two strokes with bugger all maintenance, and since the advent of CD ignition systems, zero plug fouling.



Could you provide some corroboration of the relative lifetime claim?



Jim

+1

I've got two two stroke outboards.. both have a lot of use, no real maintenance beyond impeller changes and lower unit lube, neither one fouls plugs nor needs a rebuild.


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[Dockhead]

Originally Posted by Sailmonkey

+1

I've got two two stroke outboards.. both have a lot of use, no real maintenance beyond impeller changes and lower unit lube, neither one fouls plugs nor needs a rebuild.


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+2

Plug fouling disappeared on two strokes 30 years ago.

Various two stroke engines in my ownership over the last 20 years have been totally reliable, never a problem of any kind.

My previous 25hp two stroke Mariner was already starting to rust apart when I sold it, but it would start with a half pull on the starting cord, first time, every time. The electric starter was completely superfluous.

I did lower end lube every other year, and impeller every three or even four years, and that was absolutely the only maintenance it ever got. It was one of the most reliable and utterly trouble-free items of gear I ever had on my boat.

Two strokes have radically fewer moving parts, than four strokes. I would guess 1 moving part for every 4 or 5 on a four stroke. This extreme simplicity is a really great advantage of two strokes.

[thomm225]

Originally Posted by Jim Cate

I find that hard to believe, having had great long lives from various two strokes with bugger all maintenance, and since the advent of CD ignition systems, zero plug fouling.

Could you provide some corroboration of the relative lifetime claim?

Jim

My 2 strokes.....three 1960's era 40hp Johnsons, a 40hp Mercury, 65 Mercury, and a 25 Evinrude never needed rebuilds but would get a bit smoky after a lot of use.

My 4 stroke Homelite 55hp that I owned during this period never needed a rebuild and never smoked etc. I did change the lower oil seal on the power head on the Homelite though due to it's leaking oil but that was it. This engine would at minimum double the fuel mileage of all the other 2 strokes I owned

Rather than rebuild any of the old 2 strokes, I'd sell and get another as you can see above (I owned all those between ages 16-24 years old) Some guys didn't care about the smell and smoke and would use a low priced old outboard until in gave up

My current outboard is a 2011 Mercury 5 hp 4 stroke with 25" shaft which is the main engine on my sailboat. In the 5 years I've owned it, I've changed the oil 2X , lower unit oil 2X, and impeller 1X otherwise nothing not even a new plug.

It could be time to get up to date on your engines and let the bygone days of inefficient smoky, smelly 2 strokes go.

I'll never forget that on the pop cover of my last 40 Johnson the instructions were to add a quart of SAE 30 to six gallons of gas. (24:1 ratio) This was one of the oldest 2 strokes I owned. The pint sized 2 stroke oil was available at this time ........but I tried it once and it left quite the oil slick upon startup. I can't image what 16:1 ratio would look like

http://www.evinrudenation.com/owner-...out-outboards/

From the article above:

1) What is my fuel/oil ratio?

Johnson and Evinrude carbureted 2-stroke outboards since 1964 require a 50:1 fuel to oil mixture (2%) on engines without an automatic oiling system – 6 gallons of gas to 1 pint of outboard oil. Refer to question #5 for information on oil.

Most outboards manufactured before 1964 need 24:1. Fishing motors prior to 1955 commonly used a 16:1 ratio. Refer to question #20 for more information about older outboards.

[Sailmonkey]

Here's the problem. You're comparing outboards of the sixties to something built in the 21st century. I've got a 2002 2hp mariner and a 2005 5hp mariner. The 2 is a little smokey ( I admittedly may have added a wee bit too much oil on accident), but the 5hp, when used daily smokes for about 10 seconds on startup then it's done. In a year of daily use the 5 never fouled a plug, or did anything other than run without complaint.

And now that it spends more time in storage than running, it will still run without carb jet clogging like the 4strokes.


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[thomm225]

The point is that we may as well keep evolving toward cleaner running engines as in the past. See below:

1) What is my fuel/oil ratio?

Johnson and Evinrude carbureted 2-stroke outboards since 1964 require a 50:1 fuel to oil mixture (2%) on engines without an automatic oiling system – 6 gallons of gas to 1 pint of outboard oil. Refer to question #5 for information on oil.

Most outboards manufactured before 1964 need 24:1. Fishing motors prior to 1955 commonly used a 16:1 ratio. Refer to question #20 for more information about older outboards.

It only makes sense now for the next step to be four stroke engines which are so much more efficient and clean running than two stroke

We did the same thing with lawn mowers back in the day. I had a four stroke Briggs and Stratton on the mower I used to earn cash money with when I was 11-14 years old, but my cousins who lived with their grandparents used a two stroke mower since granny still had one.......

Today most all mowers are 4 stroke.

but I can understand some old folks not wanting to change the way they've always done it......

[Sailmonkey]

If the weight continues to come down, I'd like to own a 4 stroke outboard. But my two hang ups at the moment are weight/bulk, and to a lesser degree carb fouling. A 6hp Suzuki is almost close enough in weight to my old 5hp for me to switch when the 5 horse dies. But the 2horse, no way......I keep that thing for when I want an engine I can set on the stern rail with one hand on the lower unit. And I'm in good shape, still on the good side of 40.


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[Dockhead]

Originally Posted by thomm225

. . .but I can understand some old folks not wanting to change the way they've always done it......

Ha, just wait until direct injection trickles down to small outboards. Four strokes outboards will disappear!

Two stroke is inherently superior -- lighter, simpler, higher power density -- but for the issue of unburned mixture getting out the exhaust tract. This is solved with direct injection.

[thomm225]

Originally Posted by Dockhead

Ha, just wait until direct injection trickles down to small outboards. Four strokes outboards will disappear!

Two stroke is inherently superior -- lighter, simpler, higher power density -- but for the issue of unburned mixture getting out the exhaust tract. This is solved with direct injection.

A two stroke is still very inefficient as far as fuel consumption. Even my old 60's model four stroke Homelite 55hp could out perform todays two stroke outboards in that area......

https://www.youtube.com/watch?v=itFuBN72kxo

https://www.youtube.com/watch?v=4gUnhcYLTdE

[Dockhead]

Originally Posted by thomm225

A two stroke is still very inefficient as far as fuel consumption. Even my old 60's model four stroke Homelite 55hp could out perform todays two stroke outboards ......

Two stroke disadvantages in fuel consumption, and emissions, are both the result of unburned mixture getting out the exhaust tract.

Direct injected two strokes have better specific fuel consumption than four strokes, because there is less internal friction.

[a64pilot]

Originally Posted by Dockhead

Ha, just wait until direct injection trickles down to small outboards. Four strokes outboards will disappear!

Two stroke is inherently superior -- lighter, simpler, higher power density -- but for the issue of unburned mixture getting out the exhaust tract. This is solved with direct injection.

Not going to happen, don't forget emissions. DI two strokes have been out what at least 20 years? When was the first Orbital patent?
I thinik Mercury made the first outboard DI engine in 1995?
I love 2 strokes, have raced motorcycles most of my life, we used to disparagingly call four strokes Diesels in my Road Racing days, way down on power and HEAVY
One of my first and most loved race bikes was a Husqvarna WR-250, weighed 250 lbs. and was THE bike to beat in Hare Scrambling back then, two stroke of course there were no serious four strokes then, only Honda made a four stroke and on the track it was a joke.

Now as an old man a few years ago as I guess as sort of a mid life crisis, I bought a new Husqvarna since they had come back into production, a TE-450, weighs about 250 lbs and is a fuel injected four stroke. Let me tell you, I know we remember things being better than they actually were, it's human nature, but this new four stroke would absolutely slay my old two stroke in power, yes there is 200 more CC's, but at least double the power, and as it came out of the box it was street legal, met 2008 US emissions standards, something the old Husky's never did.

Four strokes are the future, whether we like it or not, and they will equal or surpass two strokes in power output. Fuel injection will replace carbs, just as CDI ignition replaced points, and there will be a reliability improvement with fuel injection, just like there was with CDI.
Fuel injection on a small four stroke is like magic, my Husky, I can wack the throttle wide open in first gear from idle, not bog, no stall, but you had better be hanging on, you could never do that with a carb, I don't care if you had an accelerator pump, CV or what, fuel injection is way more responsive.

Like it or not but common rail is the future of Diesel engines too and they will be more efficient, the NVH (noise, vibration and harshness) will be much less, down to automotive spark ignition levels, pollute less and overall require less maintenance.

Maybe it will be our kids that arrive in an anchorage being pushed by a Common Rail motor and get into their dinghy with a lightweight mostly plastic four stroke, but it's coming.


I motorized a couple of Dahon folding bikes to carry in my airplane and used a 35cc Honda weed wacker engine, four stroke. Let me tell you, the thing is brilliant, light weight and powerful and runs smoother than a two stroke weed wacker engine.
Honda Engines | GX35 Mini 4-Stroke Engine | Features, Specs, and Model Info

[Dockhead]

Originally Posted by a64pilot

Not going to happen, don't forget emissions. DI two strokes have been out what at least 20 years? When was the first Orbital patent?
I thinik Mercury made the first outboard DI engine in 1995?
I love 2 strokes, have raced motorcycles most of my life, we used to disparagingly call four strokes Diesels in my Road Racing days, way down on power and HEAVY
One of my first and most loved race bikes was a Husqvarna WR-250, weighed 250 lbs. and was THE bike to beat in Hare Scrambling back then, two stroke of course there were no serious four strokes then, only Honda made a four stroke and on the track it was a joke.

Now as an old man a few years ago as I guess as sort of a mid life crisis, I bought a new Husqvarna since they had come back into production, a TE-450, weighs about 250 lbs and is a fuel injected four stroke. Let me tell you, I know we remember things being better than they actually were, it's human nature, but this new four stroke would absolutely slay my old two stroke in power, yes there is 200 more CC's, but at least double the power, and as it came out of the box it was street legal, met 2008 US emissions standards, something the old Husky's never did.

Four strokes are the future, whether we like it or not, and they will equal or surpass two strokes in power output. Fuel injection will replace carbs, just as CDI ignition replaced points, and there will be a reliability improvement with fuel injection, just like there was with CDI.
Fuel injection on a small four stroke is like magic, my Husky, I can wack the throttle wide open in first gear from idle, not bog, no stall, but you had better be hanging on, you could never do that with a carb, I don't care if you had an accelerator pump, CV or what, fuel injection is way more responsive.

Like it or not but common rail is the future of Diesel engines too and they will be more efficient, the NVH (noise, vibration and harshness) will be much less, down to automotive spark ignition levels, pollute less and overall require less maintenance.

Maybe it will be our kids that arrive in an anchorage being pushed by a Common Rail motor and get into their dinghy with a lightweight mostly plastic four stroke, but it's coming.


I motorized a couple of Dahon folding bikes to carry in my airplane and used a 35cc Honda weed wacker engine, four stroke. Let me tell you, the thing is brilliant, light weight and powerful and runs smoother than a two stroke weed wacker engine.
Honda Engines | GX35 Mini 4-Stroke Engine | Features, Specs, and Model Info

I really doubt that four stroke, Otto cycle, spark ignited engines are the future. Diesels and Atkinson cycle engines have SO many advantages.

For small engines where weight is critical, my money is on two strokes. Direct injection and different scavenging systems have really solved the emissions problem. Two stroke diesels have similar advantages. See for example Road & Track, "The Humble Two Stroke Might Be the Engine of the Future", http://www.roadandtrack.com/new-cars...-turbo-diesel/



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[a64pilot]

Issue with Atkinson cycle engines is they have zilch for torque, won't pull the hat off of your head, they work with Hybrids as the electric motor can provide the torque for acceleration, and many Otto Cycle engines can emulate an Atkinson cycle with valve timing once up to speed, that you are already seeing on the road, just they have silly assed marketing names so Igmo has no idea what they are driving.

I didn't read the R&D article, but bet that 2 stroke Diesel is like a Detroit as in it has an exhaust valve, regular piston port two strokes whether reed valve or not don't exhaust scavenge very well, that is what the expansion chamber is for, plus a pressure oil lubricated, blown two stroke Diesel has almost nothing at all in common with a mix the oil with the gas to lubricate the thing regular two stroke.

No, the two smoke had it's day, it was real simple, easy to produce and made good power, just burned lots of fuel and polluted.
Little outboards will go the way their big brothers did, to four strokes, and for the same reasons. Least that's my bet.
There have been "miracle" engine designs for as long as I can remember, but where are they? Literally none have made it into production, long term.
Heck the opposed cylinder Diesels were prior to WWII and I think many US subs initially had them, but where are they now?
https://en.wikipedia.org/wiki/Opposed-piston_engine

[belle-isle]

Originally Posted by Sailmonkey

Here's the problem. You're comparing outboards of the sixties to something built in the 21st century. I've got a 2002 2hp mariner and a 2005 5hp mariner. The 2 is a little smokey ( I admittedly may have added a wee bit too much oil on accident), but the 5hp, when used daily smokes for about 10 seconds on startup then it's done. In a year of daily use the 5 never fouled a plug, or did anything other than run without complaint.

And now that it spends more time in storage than running, it will still run without carb jet clogging like the 4strokes.


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I agree with you on the fact that comparing a 60's 2-stroke and a 21st century 4-stroke is clearly biased. Not only that but one factor (which may be critical, or not, depending on a specific user's needs) is also not addressed by this latest comparison: weight.

This thread has clearly established that 4-strokes are superior in fuel efficiency and 2-strokes are superior in lightness. Personally, the latter one is more important to me and I'm willing to pay more fuel and spend an extra fee seconds adding oil for that. And I totally understand that for others in different circumstances (like not having to haul the engine up and down a pushpit in choppy waters), fuel efficiency could be the main driver.

Like all things on a boat, outboards are a matter of compromise...


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[Dockhead]

Originally Posted by belle-isle

. . . .This thread has clearly established that 4-strokes are superior in fuel efficiency and 2-strokes are superior in lightness. . . . . .

True of currently available small engines with carburetors.

But direct injection and different scavenging techniques have changed everything. You can already buy direct injected two strokes from BRP (Evinrude) which achieve about 300g/kWH, which is in line with good modern fuel injected four strokes. That amounts to converting about 28% of the heat in the fuel into mechanical power. The very best spark ignition engines only achieve about 225g/kWH (Prius Aktinson cycle engine). Compare this to modern common rail high pressure turbo diesels -- 198g/kWH (BMW 2 liter), or the most efficient internal combustion engines in the world, which are large two-stroke diesel ship engines from MAN and Wartsila, which get to 155g/kWH, which is more than 50% efficient.

See: https://en.wikipedia.org/wiki/Brake_...el_consumption


Two stroke engines are being developed for cars, too. Lotus is already running a two stroke engine which has better specific fuel consumption than any four stroke spark ignition engine. They say:

"Jamie Turner, Chief Engineer of Powertrain Research at Lotus Engineering said: 'The automotive industry, including Lotus Engineering, has quite rightly advocated engine downsizing for four-stroke engines. This is as a result of the dominance of the four-stroke cycle in the automotive world and its generation of throttling losses at part-load, where vehicles run most of the time. The two- stroke cycle, conversely, does not suffer from significant throttling losses and in many ways is a more natural fit for automotive use. With the thermodynamic disadvantages of throttling losses removed, the two-stroke engine is free to be sized according to its improved part-load fuel consumption. Downsizing therefore isn't vital and, due to the improved light-load efficiency and emissions performance we see with Omnivore, this technology approach and 'upsizing' could permit a more efficient engine.'"

Lotus' Omnivore engine is already 10% more efficient, with more to come - Autoblog

See also: Two Stroke Engine - Internal Combustion Engines (IC) - Automobile Magazine

And that's with only half the problem solved -- new scavenging techniques offer even more room for development. The remarkable EcoMotors opposed piston engine is a two stroke. With all due respect to my friend A64, it's the Otto cycle spark ignition engine which has had its day, and is somewhere near the end of its development road -- two strokes have far more development potential. We shall see.

[a64pilot]

I will make a prediction that the last automobile either Dockhead or I ever buy, will be powered by an Otto cycle engine, it may emulate the Atkinson cycle with variable valve timing, but it will be an Otto cycle.
I have heard of the demise of the Otto cycle engine forever, there is always a new exciting technology just around the corner, whether it be a Wankel, a turbine, opposed piston, steam etc. Just never quite meets expectations.
The GM small block I predict will still be in production after I'm gone.

Way, way back in the day I made my living building and drag racing motorcycles.
The last serious 2 stroke bike I raced against was in Gulfport Mississippi for the World finals, 1980 maybe? I remember the guy, Paul Gast I think, had a shop in NY called Fast by Gast. Fastest two smoke I have ever seen, just not quite fast enough
It was an H2 Kawasaki on Nitrous Oxide, I was on a Kawasaki 900 with a Turbo.
The two strokes cannot match the HP output of the four strokes, the HP per weight of a modern four stroke and reliability is greater than a two stroke is capable of.

Two strokes are not necessarily lighter than four strokes, that is changing. Electronic Fuel injection is a whole nuther world.

Time will tell