2 strokes

[Csail]

Why are they banned? what difference does it make wheather the oil is mixed with the fuel or injected on a 4 stroke?

 

[Lakesailor]

4 strokes have a recirculating pressure oil system that supplies oil to the bearings and moving parts. The cylinder walls are lubricated by splash lubrication from below the piston.
Two strokes use a total loss system in which the oil having lubricated the bearings etc is scavenged to the combustion chamber and burned.
This makes it near impossible to get the motors under the emissions regs levels.
They could be engineered to do it, but on a small value item like a low-power 2 stroke it isn't viable.

 

[dylanwinter]

As I understand it

As I understand it it is to do with the two stroke cycle - an incomplete burn

http://en.wikipedia.org/wiki/Two-stroke_engine

so they can offer a higher power to weight ratio and are often more reliable as they have fewer moving parts and offer power every other stroke - as opposed to every fourth stroke on the four stroke

I had heard that the RNLI have a special dispensation to carry on using and buying two strokes

I spent three winters on the Broads - the first weekend I used an old 2hp two stroke seagull

you start it by dribbling oil and petrol into the water and then it puts out a continuous spray of partially burnt fuel

I felt so bad about what it was doing to the water that I went out and bought a Honda four stroke - I had a good job at the time so I could afford one

wonderful little engine

if you want to see how bad a seagull can be....

http://www.keepturningleft.co.uk/video-logs/ktl-vlog-137-the-unethical-use-of-a-seagull/

and a little honda really shoves the slug along at a cracking pace

http://www.keepturningleft.co.uk/video-logs/ktl-vlog-139-honda/


Dylan

 

[VicS]

Why are they banned? what difference does it make wheather the oil is mixed with the fuel or injected on a 4 stroke?

They are not banned.

The conventional premixed fuel two strokes with which we are familiar do not comply with the emissions regulations which came into force in 2007 (??) as part of the European Recreational Craft Directive.

That only applies to recreational craft so in theory it does not apply to commercial use, or to rescue or safety use hence does not in fact apply to the RNLI.

Mercury and Mariner and also Bombardier ( Evinrude) produce 2 stroke outboards ( Optimax and E-TEC) which comply with the emissions regulations but only in the larger HP ranges.

Other similar emissions regulations apply in other counties

The RCD also imposes emissions limits on diesel engines and also includes limits on noise.

 

[electrosys]

Why are they banned? what difference does it make wheather the oil is mixed with the fuel or injected on a 4 stroke?

The restrictions on the sales of new 2-strokes (which is not exactly the same as 'banning' their use - well, not yet) applies to engines for recreational marine use. You can still buy 2-stroke engines attached to chain saws, hedge-trimmers and all the rest.
Why ? 'Cause our lives are being controlled by unelected desk-bound Euro-bureacrats who have nothing else better to do than legislate in order to justify their existence.

2-strokes burn a little oil. Diesel engines - the most common form of marine propulsion - burn 100% oil as their fuel. The difference is that 2-stroke oil burning is visible - therefore it's mindlessly easy to focus upon that.

The exhaust products of diesel engines are still there - in the atmosphere and in the water - let's not kid ourselves otherwise - it's just that they are not so visible as 2-stroke smoke.

 

[prv]

Why are they banned? what difference does it make wheather the oil is mixed with the fuel or injected on a 4 stroke?

4-strokes don't inject oil into the cylinder. You may be thinking of some larger two-strokes which have separate oil and fuel tanks instead of using pre-mixed.

4-strokes keep all (in theory) of their oil inside them, rather than burning it.

Pete

 

[Lakesailor]

I'm glad you agree.

 

[ProDave]

The conventional premixed fuel two strokes with which we are familiar do not comply with the emissions regulations which came into force in 2007 (??) as part of the European Recreational Craft Directive.

That only applies to recreational craft so in theory it does not apply to commercial use,

So, playing devils advocate, this is purely a RCD issue.

My boat is old and so pre dates the RCD so the RCD does not IN ANY WAY apply to my boat.

So shouldn't I be able to buy a brand new 2 stroke OB to replace my existing one should it ever break down because I don't have to comply with the RCD.

 

[Sans Bateau]

I think its environmental rather than RCD.

 

[VicS]

So, playing devils advocate, this is purely a RCD issue.

My boat is old and so pre dates the RCD so the RCD does not IN ANY WAY apply to my boat.

So shouldn't I be able to buy a brand new 2 stroke OB to replace my existing one should it ever break down because I don't have to comply with the RCD.

This 'ere is asummary of what the RCD says in connection with 2stroke outboards

I think you will find that it does apply to the manufacture/ import/sale of all engines within the EU for use in recreational craft, regardless of whether or not the craft itself is/was RCD compliant.

If you want all the i's dotted and t's crossed you will have to read the RCD.

I'm not sure if you will find the entire document on line or not. You may have to buy it, although I did at one time find quite a bit of info but I do not now have a link.

 

[Rigger Mortice]

I've recently replaced a 2 stroke with a 4 stroke and I've found the new engine to be far better than the old 2 stroke. Fewer fumes, quieter, more powerful and significantly better fuel consumption.....approaching 40% better. Add to that a lower bill for oil and, on running costs alone the engine justifies itself.

I reckon that the only case for having a 2 stroke is where the power/weight ratio may justify it...but on a saily boat I don't think that applies.
The reverse applies on a tender with a small 2-3 hp engine which is only used for short distances. I don't think there's any point in having a four stroke.....despite what the bureaucrats tell us.

 

[macd]

My understanding is that it was nothing to do with RCD, although RCD may subsequently have taken it on board. The following was put out as a press release some years ago, and sums up the then situation:

"European EU2006 emission regulations
EU 2006 Emissions Standards Label represents conformity to the EU emissions standards proposed by the Commission of the European Communities on 12th October 2000. ALL engines sold PRIOR to the implementation of the standards may continue to be used. ONLY the EU standard is relevant to the UK and the rest of the EU. Manufacturers often refer to other standards such as EPA and CARB which only refer to the US market and have no relevance to the UK. Effectively, from 1st January 2007, NEW conventional carburettor / E.F.I. 2-strokes will cease to be sold in the UK and the rest of the EU, as they will not meet the standards. Equally, only four strokes which meet the regulations may be sold from 1st January 2006. It should be noted that the four strokes are required to meet the regulations a year earlier than 2-strokes. (For more details see "Emissions: The Truth") Unlike the EPA and CARB standards, the EU 2006 standard covers three constituents of exhaust emissions, and noise levels. The exhaust emissions included are nitrous oxide and hydrocarbons (as included in EPA & CARB standards) plus carbon monoxide. Consequently the EU 2006 standard is the most difficult to attain compared with EPA and CARB. Unlike the US standards which allow a percentage of ‘dirty’ engines to be sold, the EU 2006 standard, will effect EVERY NEW engine sold in the EU."

Two-strokes exhausts, incidentally, are intrinsically quite low in oxides of nitrogen ('smog gases'). Their Achilles heel is unburnt hydrocarbons (not just lubricating oil but also unburnt petrol). As other posters note, this is remediable (typically using direct fuel injection where the fuel is injected into the cylinder AFTER the exhaust port has closed), but at considerable expense, making it uneconomic for small 2-strokes.

It is perfectly legal for a private individual to use such a 2-stroke, but new ones may not be offered for sale.

 

[electrosys]

It is perfectly legal for a private individual to use such a 2-stroke, but new ones may not be offered for sale.

... after existing stocks are depleted.

Some canny chandlers saw this coming and bought substantial stocks before the cut-off date (just like I did with tungsten filament lamps).

And - I believe the rules only apply to new complete engines - it's still ok to import/sell parts for existing engines - so in theory, you could build yourself a completely new 2-stroke engine from newly imported parts - if you were of a bloody-minded nature.

Either that, or buy from outside the EU and bring 'em back in - I doubt that anyone would check.

 

[macd]

Some canny chandlers saw this coming and bought substantial stocks before the cut-off date

Indeed they did, god bless 'em.

 

[prv]

in theory, you could build yourself a completely new 2-stroke engine from newly imported parts - if you were of a bloody-minded nature.

Bet it would cost you a lot more than a complete engine though. Unfortunately, since otherwise I'd be happy to do it.

I've known the Army build a complete new Landrover from spares.

Pete

 

[Rigger Mortice]

And - I believe the rules only apply to new complete engines - it's still ok to import/sell parts for existing engines - so in theory, you could build yourself a completely new 2-stroke engine from newly imported parts - if you were of a bloody-minded nature. .

That makes me wonder why some enterprising dealer doesn't do a deal with likes of Mariner. If they imported two "assemblies" (which happen to be the top half and bottom half of a complete engine), we could buy the two halves separately, bolt them together and voila!
I'ld be happy to do it when my small 2T outboard finally gives up the ghost.

 

[charles_reed]

We all know about the pollution caused by 2-strokes.
It was a study, of the Florida Everglades in the late 60s which proved that the single most polluting source degrading the environment was the exhaust from 2-stroke OBs. The final nail in the coffin was provided by OMC's chief designer.
The RCD is merely a me-too stemming from that.
The second greatest source of environmental degradation pollution is caused by ionic surfactants - so stop washing down your boat and ladies belay washing up

 

[charles_reed]

... after existing stocks are depleted.

Some canny chandlers saw this coming and bought substantial stocks before the cut-off date (just like I did with tungsten filament lamps).

And - I believe the rules only apply to new complete engines - it's still ok to import/sell parts for existing engines - so in theory, you could build yourself a completely new 2-stroke engine from newly imported parts - if you were of a bloody-minded nature.

Either that, or buy from outside the EU and bring 'em back in - I doubt that anyone would check.

Gray imports are still available (to my knowledge) in France, Italy, Greece, Spain and Malta.

The usual thing is to go to Tunisia and buy one over the counter.

Of course, if in the UK.....

 

[electrosys]

It was a study, of the Florida Everglades in the late 60s which proved that the single most polluting source degrading the environment was the exhaust from 2-stroke OBs. The final nail in the coffin was provided by OMC's chief designer.

Yep - can quite believe it - the Everglades: 100% representative of the marine environment world-wide.

 

[macd]

It was a study, of the Florida Everglades in the late 60s which proved that the single most polluting source degrading the environment was the exhaust from 2-stroke OBs.

I don't doubt the veracity of your reference for a moment, but the single most degrading source of damage to the Everglades is urbanization and all that goes with it.