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So what's the deal with EURO4 2-strokes?

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Easy-X
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PostPosted: 22:13 - 03 Apr 2019    Post subject: So what's the deal with EURO4 2-strokes? Reply with quote

A year or so ago I read an article somewhere decrying the death of road legal 2-strokes (as new purchases) due to emissions regulations.

Apparently they employ some nebulously termed "electronically controlled carburettor" (along with one or more cats.)

Is this some ECU controlled hybrid between carb and fuel injector or just a stepper-motor on the throttle "fly by wire" style? I'm assuming if cats are involved there's an oxygen sensor on the exhaust which sounds a bit tricker to place compared to a 4-stroke exhaust.

Curious as to how these new bits affect the traditional 2-stroke performance. (I doubt it's like comparing 4-stroke EFI to carbs.)
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Pjay
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PostPosted: 23:40 - 03 Apr 2019    Post subject: Reply with quote

This might help:
https://scooterlab.uk/new-euro-4-2-stroke-peugeot-released-news/
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stevo as b4
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PostPosted: 23:53 - 03 Apr 2019    Post subject: Reply with quote

Why exactly do you want to know?

If your considering buying a new 50cc two stroke with electronic carbs, fuel injection and emissions control then hurry up as they won't be around much longer. Two stroke engines are dead and a thing of the past only, and all the screaming whinging babies in the world won't change that.

If your wanting such a two stroke to fiddle with and modify then simply don't bother. Bottom line is that Euro 3 and 4 two stroke bikes are pretty crap and a shadow of their predecessors in performance, and drivability.

I don't know much about 50cc current bikes, but the few new Road legal 125's between around 2007-2012 that were on sale and had all this electronic emissions control and exhaust catalysts run like shit, and are at best about 20-25% down on power.

Two stroke engines don't like being clogged up with restrictions, and you can't lean fuel them to make them cleaner but you can't run an engine rich with a catalytic converter either. Some of these bikes are impossible to de-restrict fully without replacing the carb, exhaust and the whole ignition system too.

My two stroke bikes are 31 and 33years old, and generally they are far better performing than very late model two strokes with lots of electronic and exhaust system interference.

If you want a 50cc tinkering bike then either get a simple older air cooled one that is easy to mess with, or something like a Derbi Senda or Aprilia RS50 with thier very tunable liquid cooled popular engines.

I think Euro anything is Barking up the wrong tree.
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Easy-X
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PostPosted: 01:36 - 04 Apr 2019    Post subject: Reply with quote

What is it you are reading? I didn't mention anything about buying bikes or 50cc.
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Ste
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PostPosted: 02:05 - 04 Apr 2019    Post subject: Reply with quote

HardlyDavidson wrote:
I didn't mention anything about buying bikes or 50cc.

Yeah but that is why you're asking about two stoke Euro 4 stuff, right?
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Easy-X
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PostPosted: 03:24 - 04 Apr 2019    Post subject: Reply with quote

Nope, just curious. I thought this was Bike Chat Forums not Bike Psychoanalysis Forums Razz
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Ste
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PostPosted: 03:26 - 04 Apr 2019    Post subject: Reply with quote

From the bottom of the page that stevo linked to:

"Euro 4 KTM 250/300 2-stroke

Peugeot isn’t the first company to come out with a modern Euro 4 injected 2-stroke engine. KTM’s 2019 range includes their 250/300cc EXC TPI motocross bike. TPI stands for Transfer Port Injection. The off-road machine is clean burning and meets Euro 4 standards, proving that it’s possible to build a powerful 2-stroke engine that can still meet the latest emissions standards.

One of the major benefits from an injected 2-stroke is that unlike a carb fed motor there’s no need to jet the bike for different temperatures, riding conditions or state of tune – something many of us tuned scooter riders would benefit from on the road.

Maybe the future is orange after all…"

Get one of those.
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Easy-X
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PostPosted: 03:28 - 04 Apr 2019    Post subject: Reply with quote

Pjay wrote:


Thanx, I've found a few articles like that "hey guys! we got the solution!" but only a cursory explanation of how it works. So far I've seen mentions of TPI which sorta looks similar to a typical 4-stroke carb to EFI "upgrade" i.e. throw away carb and replace with throttle body and a port fuel injector. Then there's the "electronically controlled carb" in Derbi's specs. Is that just a dumbed down label for TPI?
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stevo as b4
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PostPosted: 09:33 - 04 Apr 2019    Post subject: Reply with quote

Awkward middle age man or as said another Tara?

What are you trying to do, design and engineer a new saviour to the two stroke engine? But an EFI two stroke to mess with in the shed? Convert your existing bike to EFI? There's always a reason why people want to know stuff, so there's no point in trying to be all cryptic and obstructive.

Electronic carbs, have one or more circuit that has a jet that is controlled by a solenoid operated valve. They usually are on the idle circuit or a power jet or both. And they are linked to an ECU that has control of the ignition map and any other features like exhaust valves or exhaust temperature control.

Such systems are as old as the early Suzuki RGV 250. Its nothing new, and by todays standards not that advanced in terms of the software and electronics used. It also is a slippery slope of covering simple two stroke engines in sensors and unnecessary electronic crap that isn't going to give them any more peak power, mechanical reliability, or huge gains in fuel consumption and particularly emissions.

EFI into a throttle body intake is basically a better version of a carb, in that with good ECU mapping and loads of sensors you can get more ideal fueling over a wider range of conditions and situations such as ambient temperature and altitude etc. Its very possible to fit this to two strokes, but it's again eating away at their light weight and simple benefits.

When you get to TPI and then extremely difficult DI systems, then you get lots more problems to solve and can make a two stroke worse in some aspects as well as ramping up the complexity so much it's diminishing returns.

You can't make a petrol fueled two stroke clean enough to be acceptable and have a serious future while they burn any oil at all. KTM know this better than you or I and are just padding into the tide for as long as they can before it becomes economically un-viable.

The thing to remember is that there's no reasonable life saving cure for the two stroke engine. Its dead technology and huge companies have spent millions trying to get away from this inevitable end, and realise it's not worth it, and more so that people won't race to accept and adopt them in today's climate.

You can design a two stroke engine that has a wet sump and needs to burn no oil to speak of in combustion. You can also scavenge them far better and more efficiently than using pressurised crankcases and fancy shaped big fat exhausts. But you have now built an engine more complicated and expensive to build than a four stroke engine you could have started with in the first place. See the logic in that?

Making four strokes more efficient or less polluting and more economical is extremely difficult now as it is, why would anyone want to shoot themselves in the head trying to do this with a two stroke? There's a reason why there are no direct fuel injection superbikes, and it's not all about weight and cost.

The limited time left for ICE engine development is in going back to early principles of going slow, purging spent gases more completely , and trying to not waste any energy as heat.

Fucks sake I've just turned into Teff. Doh!
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bhinso
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PostPosted: 10:11 - 04 Apr 2019    Post subject: Reply with quote

B0ndy wrote:
https://i.imgur.com/H3kho8z.png
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Easy-X
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PostPosted: 12:04 - 04 Apr 2019    Post subject: Reply with quote

stevo as b4 wrote:
...Fucks sake I've just turned into Teff. Doh!


LMAO!

There are a few videos on YouTube where similar model carb vs TPI comparisons are made but they're a bit light on detail. The general (maybe paid for) message is that there's very little performance difference but you do get better efficiency and emissions at the cost of extra electronics. For some reason I don't trust these videos - feels more promotional than informational.

But yes, I take your point on the convergence: add an ECU, TPI, fuel pump, oil pump, sensors, etc. and you have almost the same setup as an EFI 4-stroke...

However, 2-stroke isn't 4-stroke and while there's still some love for the beast it'll hopefully keep going... somehow. Feck! There's plenty of talk of bringing back emission-friendly rotary engines. Welcome back, Mazda RX Smile (This time with a combo of both port and direct injection so I've heard.)

I'm not sure how I feel generally about this chase for low emissions. There's a certain elegant simplicity in, for example, a single cylinder carb fed engine especially 2-stroke. Certainly the "low carbon footprint" is a total sham IMHO but NOx is sadly a thing killing ppl right now Sad Apologies for being such a tree-hugger.

There's a certain gloomy inevitability about it all but while having an ECU control a 2-stroke seems like blasphemy now it's rapidly become the norm on 4-stroke bikes and has been just the way it is on cars for ages.

As an aside I'm surprised manufacturers don't have OBD2 bluetooth built-in and their own branded variant of the Torque app. Maybe "app-connected" is way to attract the "youth" back to bikes?
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Jmoan
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PostPosted: 17:31 - 04 Apr 2019    Post subject: Reply with quote

What about different engine fuels like hydrogen or LPG for cutting down on emissions while keeping the fun of of 2 strokes?
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PostPosted: 19:58 - 04 Apr 2019    Post subject: Reply with quote

Jmoan wrote:
What about different engine fuels like hydrogen or LPG for cutting down on emissions while keeping the fun of of 2 strokes?


I think technically it could be done but certainly with the case of hydrogen it needs to be stored in a high pressure container. I wouldn't fancy strapping that to the back of a bike! Stashing it safely away in the boot of a car sounds much more practical.

Having said that boffins have created some clever "solid" tanks that are actually some funky nano-honeycomb lattice that can theoretically store hydrogen in a greater density that a straightforward tank. Safer too...

When such magically stuff might appear? Probably up there with fusion reactors Sad

A good "green" alternative fuel that's hardly used in Europe but much more popular in other parts of the world is Ethanol.

Ethanol has something like 80% of the energy density of petrol - not too bad a loss - burns cooler and only requires a re-map for EFI vehicles (maybe a better fuel pump as you need to shift a bit more of it per cycle.) With a decent ECU and flex-fuel sensor you can even mix petrol and ethanol in the same tank.

In the UK up to 5% of what you squirt out of a petrol pump is already ethanol. In 'murica it's a pretty random proportion (up to 15%) which can actually be a bit of a problem for older cars.

Ethanol is distilled from grain crops (much the same as making vodka) so it pays lip service to the tree huggers but unfortunately it still creates carbon dioxide and NOx but does it slightly better than petrol. Big bonus with ethanol though: zero particulates.

LPG is somewhere between hydrogen and ethanol with regards to pollutants but as with hydrogen, I don't think the storage suits a bike.
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