Will two strokes come back?

[elcamino12sec]

Just wondering if any of you keep up on outboard engines. If any of you boat then Im sure you understand and have experienced the difference between two stroke and four stroke outboards and how they perform. There is quite a bit of technology in two strokes with outboards like the new Evinrude E-Tech and some of the other HPDI two strokes. If any one has driven a naturaly aspirated four stroke outboard you understand that "in genral" the two strokes out perform the four strokes. Does any one know or think that any of this technology will ever make it into the offroad scene in years down the road or do you think they will stay four stroke? I could not immagine how fast a high preassure fuel injected 250cc two stroke would be, and fun too! Oh, and this is not intended to be a two vs four stroke thread, just general tech stuff.

 

[19Brendan81]

The most powerful and efficient motor in the world is a supercharged diesel 2 stroke that is used in ships. It comes in enormous displacement, multi cylinder varieties rated up to 110,000 horsepower. It has over 50% thermal efficiency which is about 15% better than the most efficient 4 stroke. This is the sort of technology that companies should be looking at for single cylinder 2 strokes, the direct injection part being a real winner. There is massive potential to make awesome clean and powerful small 2 strokes....someone just needs to do it!

Sooner or later the thousands of bandwagon jumpers who got onto the 4 stroke scene will realise that whilst the thumpers are good when new, once they get a bit old they become extremely expensive and difficult to repair in comparison to equivalent 2 strokes.

 

[DannyMoto07]

I've always found this topic interesting on many different levels. Diesel, even though it's efficient and getting cleaner by the day has it's technology based on heat. Therefore you need massive weight to compensate (cast iron). Thus making weight an issue.

Four-stroke gas is great, cleanish and torquy, however there are SO MANY power-robbing moving parts. Cams, valves, rockers, springs, rods.. etc. etc.

Two-stroke gas motors can be all aluminum or magnesium making them extremely light weight, and the only moving parts are the reeds (if equipped) and the piston. I think the reason most people are scared about two-strokes is the fact that they do not have a designated sump to lubricate the motor... they're based on a mix-only lubrication system. I think this stigma on motor seizure, difficulty in tuning, and the fact that they BURN oil is what's holding 2-strokes back.

People need to realize that 2-strokes are very clean, easilly tunable, lightweight, torquy, full of potential horsepower, and are the highest revving motors on the planet (next to gas-turbine motors).

I've tuned many a 50cc 2-stroke, decked heads, ported motors, built my own reeds, and they are by-far the best bang-for-your-buck modifiable motors on the plannet.

Gratned, 4-strokes have their place too... I would never want a 2-stroke lawnmower. Simply imagine the potential of a car like the Geo Prizm, Toyota Echo, or even the Smart cars... A 500cc 3-cylinder 2-stroke would be perfect.

But that's just my opinion...

Dan

 

[uts]

The problem with traditional 2 stroke engines is that they emit unburnt fuel. This is much worse pollution than burnt fuel gas.(obviously they burn a lot of fuel to).
When they perfect direct injection 2 strokes for bikes, the smokers will be back, and we can farewell those new age thumpers that eat up crazy amounts of money.

 

[76GMC1500]

No, but they won't die, either.

 

[DannyMoto07]

I think there needs to be more development in expansion chambers and "boost" bottles in order for there to be less unburnt fuel.

The combination of sound-wave technology mixed with the vaccum in a boost bottle greatly lessens the ammount of unburnt fuel.

Another problem with 2-strokes is the excess in carbon they produce as a bi-product of the mix oil. However, this too can be countered with the development of a exhaust-port mounted catalytic converter. This way, most carbon particles will deposit close to the head, where it's hot and stay off of the inner walls of the exhaust. Plus, being so close to the head, the heat will help burn out the particles trapped in the converter.

I know they've experimented with this on some newer mopeds and scooters, however they put the converter near the exhaust tip and it tends to clogg.

Dan

 

[Octane250F]

The only problem with the FI 2-strokes is that they have a reputation for going through pistons and rings like crazy.
I know that BRP had lots of issues with flaking rings in their SDI 2-stroke snowmobile engines and that you usually only get about 5,000 miles out of the engine before the pistons, rings and seals are shot.
Considering how a snowmobile operates in clean air, just how long would a FI 2-stroke last with all the dirt those motors suck in?
If I can get 200 hours out of a 4-stroke (which I know is a very realistic expectation if you change the oil often), Im happy. Im not too keen on owning a 125 that needs the topend replaced every 30-50 hours.

 

[Rhein]

Yes, the technology is there. BRP and Rotax are leading the way in non motor cycle 2t development. Doc, posted their KTM converted to DI which is amazing. The DI 2Ts are 2008 CARB compliant too. The only problem 2t lovers face is mass production, hopefully KTM will do something with Rotax and get this going. It is a matter of time now. There are NO more hurdles besides a company implementing this technology. Doc did it with "off the shelf" parts off the E-Tec, so it is not expensive per say.

 

[rmc_olderthandirt]

I do a lot of boating as well as dirt biking. I am well aware of the two stroke issue on outboards. The sale of new two stroke outboards have been banned in California for years and it has now spread nation wide. Two stroke PWCs are banned from many areas.

The push to erradicate two strokes in general is strong and gaining strength. California already imposes some major restrictions on dirt bikes that don't meet the EPA guidelines, which none of the two strokes do. In California, a two stroke bike from years 2003 on are banned from MANY riding areas for a majority of the year.

So far, weed trimmers and leaf blowers have escaped the ban only because of the hue and cry from all the gardeners. The tide is rising, however, and you can only shovel sand against the tide for so long.

The direct injection two stroke systems have potential, but they don't totally solve the problem because there is still oil getting into the combustion chamber which doesn't burn completely. The direct injection systems still need more development as the existing models have proven to be very unreliable.

Rod

 

[Chili]

California already imposes some major restrictions on dirt bikes that don't meet the EPA guidelines, which none of the two strokes do.

Can't say that I'm currently up to date on the Green/Red sticker regulations but how many of the new 4 stroke MX bikes meet those EPA guidelines and qualify for a green sticker?

 

[kawicam250]

Can't say that I'm currently up to date on the Green/Red sticker regulations but how many of the new 4 stroke MX bikes meet those EPA guidelines and qualify for a green sticker?

not many, but a lot more 4T's are gettin green stickers than 2T's, thats for sure.

 

[Chili]

not many, but a lot more 4T's are gettin green stickers than 2T's, thats for sure.

Thanks but I'm looking for the actual information not a broadsided guess.

 

[2 strokes for life]

If you in California think you have it bad, just wait till 2010 in Canada. No 2 stroke powered devices exceding 100cc will not be imported to Canada. All older modles will become Grandfather titled. I personialy think this blows. Seeing how Honda almost had it down with there baja Translap. It was said that thousands of dollars money was invested to creat a cleaner burning 2 stroke but Yamaha had released their YZ400 of that year and Honda droped their project and started creating the CRF450.

 

[Rhein]

I do a lot of boating as well as dirt biking. I am well aware of the two stroke issue on outboards. The sale of new two stroke outboards have been banned in California for years and it has now spread nation wide. Two stroke PWCs are banned from many areas.

The push to erradicate two strokes in general is strong and gaining strength. California already imposes some major restrictions on dirt bikes that don't meet the EPA guidelines, which none of the two strokes do. In California, a two stroke bike from years 2003 on are banned from MANY riding areas for a majority of the year.

So far, weed trimmers and leaf blowers have escaped the ban only because of the hue and cry from all the gardeners. The tide is rising, however, and you can only shovel sand against the tide for so long.

The direct injection two stroke systems have potential, but they don't totally solve the problem because there is still oil getting into the combustion chamber which doesn't burn completely. The direct injection systems still need more development as the existing models have proven to be very unreliable.

Rod

http://www.evinrude.com/en-CA/E-Tec/E-TEC.Advantage/Cleaner.Quieter.htm

Please read the part where it says
" E-TEC even meets the ultra-low 2008 CARB (California Air Resource Board) 3-Star emissions rating. For you, it simply means a cleaner boating environment: no smoke and dramatically lower carbon monoxide emissions."

"With the E-TEC system, fuel is injected twice as fast as traditional direct injection engines and unburned fuel never reaches the exhaust port. This means the fuel charge never escapes the combustion chamber as it is burned and turned into pure power."

Please people share common courtesy and post relevant and recent FACTS, not opinions, if you are trying to make an argument.
Thanks!

 

[HubertGarfunkleIII]

Ok so I hear the 2 stroke 4 stroke debate. even though this isnt a 2 stroke 4 stroke debate but what I am wondering since it seems alot of people think the 2 stroke will eventually come back with direct injection or something like that. Matter a fact an issue of dirtrider said that the 2 stroke will come back but it will take a long time. So my question to you guys is how long do you think it will be before the 2 stroke is back on the scene? I mean are we talking 5 years or 50 years or what?

 

[2 strokes for life]

HubertGarfunkleIII, i figure 5 or so years befor the new fule injected 2 strokes come out.

 

[Rhein]

I give it 09' or so

 

[Octane250F]

Please people share common courtesy and post relevant and recent FACTS, not opinions, if you are trying to make an argument.
Thanks!

I wouldnt call quoting the BRP website posting "facts". BRP loves to stretch the truth when it comes to emissions and fuel economy on their FI 2-strokes.
I can recall BRP's infamous "2 > 4" snowmobile ad campaign that was full of half truths and outright lies.
There is no way that no unburnt fuel escapes because a 2-stroke never really completely seals the exhaust port. All that the E-Tec technology does is spray the fuel directly into the crankcase and times the release of the fuel charge into the engine much more precisely than carbs ever could.
I should also mention that FI 2-strokes use iginition timing that uses an array of sensors to adjust the ignition timing to keep the engine on a verge of siezing at all times (and thats when a 2-stroke runs its best). Its cool technology, but 2-stroke dirtbikes are known for short life already, so just how long do you think an FI 2-stroke dirtbike motor (that runs super lean all the time) is going to last? I would bet not long.

 

[Octane250F]

Can't say that I'm currently up to date on the Green/Red sticker regulations but how many of the new 4 stroke MX bikes meet those EPA guidelines and qualify for a green sticker?

I dont think that any of the MX 4-strokes made after '05 qualify for green sticker.
The only bikes that qualify for green sticker are enduro/trail 4-strokes and they are greatly choked-back compared to MX 4-strokes.

 

[HubertGarfunkleIII]

HubertGarfunkleIII, i figure 5 or so years befor the new fule injected 2 strokes come out.

well thats not too far off than at all (and thats very realistic?)Im glad I will be around to see it. If they are going to come back that quick, it seems like they wont really have much time to develop the 4t. I guess when the 2t comes back they will still be making 4t. Now that will be really cool, if we have both, great 2t and 4t. I rode my buddys new 06 4t the other day man alot more power than my 125 but, the engine is twice the size. I never rode I 250 2t, I bet 500 2t are beasts! and a blast to ride :boss:

 

[Rhein]

I wouldnt call quoting the BRP website posting "facts". BRP loves to stretch the truth when it comes to emissions and fuel economy on their FI 2-strokes.
I can recall BRP's infamous "2 > 4" snowmobile ad campaign that was full of half truths and outright lies.
There is no way that no unburnt fuel escapes because a 2-stroke never really completely seals the exhaust port. All that the E-Tec technology does is spray the fuel directly into the crankcase and times the release of the fuel charge into the engine much more precisely than carbs ever could.
I should also mention that FI 2-strokes use iginition timing that uses an array of sensors to adjust the ignition timing to keep the engine on a verge of siezing at all times (and thats when a 2-stroke runs its best). Its cool technology, but 2-stroke dirtbikes are known for short life already, so just how long do you think an FI 2-stroke dirtbike motor (that runs super lean all the time) is going to last? I would bet not long.

Are you crazy? THEY CANNOT LIE ABOUT EMISSIONS APPROVAL! DUH!

They would get sued like crazy when a customer goes to register and are told they aren't emissions approved.

After initial engine start the fuel put into the engine is metered so precisely it all burns. Carbs put excessive amounts to where it all can't completely burn. Also since it is this new fangle technology called fuel injection it injects the fuel when the exhaust port is closed.

 

[Octane250F]

Thats not what I meant. I meant they lie when they compare emissions between their 2-strokes and 4-stroke. I never said anything about emissions certifications, of course they cant lie about that.
Im sorry, but there is no engine that burns every last drop of fuel. Also, there is no way a 2-stroke can completely seal the exhaust port because the piston and rings dont give you a perfect seal.
If you know anything about engines, Im sure you realize that the piston slaps back and forth as it moves up and down in the cylinder and you are bound to get leaks.
I wont deny that FI 2-strokes are very clean, much cleaner than carbed 2-strokes, but you arguements are flawed and your claims are just downright untrue.

 

[Chili]

The entire point of my comment regarding the green/red sticker follows along the lines of where I thought Rhein was originally trying to take his point. The green/Red sticker issue is NOT a 2 stroke issue as none of the new MX 4 strokes meet the requirements either so to use it as part of the argument for the elimination of 2 strokes is inaccurate.

 

[bobbyhill925]

Can't say that I'm currently up to date on the Green/Red sticker regulations but how many of the new 4 stroke MX bikes meet those EPA guidelines and qualify for a green sticker?

The only Four stroke mx bikes getting green stickers are
yz400f yz426f 01 02 yz250 02 crf450r

 

[Rhein]

Thats not what I meant. I meant they lie when they compare emissions between their 2-strokes and 4-stroke. I never said anything about emissions certifications, of course they cant lie about that.
Im sorry, but there is no engine that burns every last drop of fuel. Also, there is no way a 2-stroke can completely seal the exhaust port because the piston and rings dont give you a perfect seal.
If you know anything about engines, Im sure you realize that the piston slaps back and forth as it moves up and down in the cylinder and you are bound to get leaks.
I wont deny that FI 2-strokes are very clean, much cleaner than carbed 2-strokes, but you arguements are flawed and your claims are just downright untrue.

I apologize let me rephrase what I said:
"After initial engine start the fuel put into the engine is metered so precisely it virtually all burns. Carbs put excessive amounts to where it all can't completely burn. Also since it is this new fangle technology called fuel injection it injects the fuel when the exhaust port is closed."

It is very obvious that the seals between rings and cylinder walls aren't perfect but they are so damn close that even arguing about it is pointless. I didn't say that they were perfect, I said the exhaust port is closed, blocked off, not open anymore, however the hell you want to put it. How much fuel can escape through that seal between a cylinder and piston is a moot point. All of your arguments are opinions with no factual documentation to back it up. Saying BRP are liars does not prove anything. I guess Yamaha, Nissan and Mercury are liars too right?

In a DI 2t engine like the Yamaha HPDI the fuel is metered precisely and is virtually all burnt. It is also injected after the piston closes up the exhaust port which is key. Watch this animation on Yami's website:
http://www.yamaha-motor.com/outboard/05pi/z300/05pi.aspx
-Highlight and click "High Pressure Direct Injection"

That is a great animation illustrating that the fuel enters when the exhaust port is closed. The insane amounts of fuel/air that would escape on a carbed 2t that created hippy emissions hysteria are not a problem anymore with this engine design. The BRP E-Tec engine also has pistons that further aid the burning of the fuel. Some DI 2ts even have the injector and spark plug placed so that the fuel hits the plug. The amounts of fuel that aren't burnt are so minuscule that they aren't a serious damper on emissions.

The flaw and superiority of a 2t engine is that it has no valves like a 4t to keep in the fuel air mix to be burnt. The DI concept bridges that gap. The metering of fuel into the engine only when the exhaust port is blocked off/closed/not open anymore allows the 2t to be dramatically better with emissions vs a sloppy carb where it just prematurely ejaculates into the expansion chamber. The DI 2ts shouldn't even need an expansion chamber anymore either as they were used to help put the escaping fuel/air charge back in the engine.

LASTLY please, tell Doc that he and his employers are liars:
http://www.dirtrider.net/forums3/showthread.php?t=86046