aaronnaland
Member
- Jan 19, 2009
- 104
- 0
2 strokes better make a comeback or else i will be owning old bikes 20 years from now.
Will The 2 Stroke Return?
- Thread starter 2004 cr500af
- Start date
Wayne Meuir
Member
- Feb 2, 2009
- 22
- 0
4-strokes are casuing one other big problem and that is that there are MANY riding parks, tracks, public riding areas, etc, that are being closed down as we speak becasue of the noise. Just do a google search on there are a number of articles/oinstances where this is or has happened in areas where 2-strokes never caused a problem. Sorta relate it so someone's car with boomer speakers--how long does it take for that to get really old? The neighbors are raising hell and getting these places closed down.
Wayne
Wayne
2strokesrock
Member
- Oct 7, 2008
- 204
- 0
biglou said:
I have been trying to explain this too my dad who thinks that you should never have to rebuild a 4 stroke, or change the oil for that matter. :)
Last edited:
jaguar
~SPONSOR~
Latest report in the mags is that 2 strokes are being considered to be allowed to compete against 4 strokes of the same engine size. (250cc 2 stroke against 250cc 4 stroke). Once that becomes commonplace then 2 strokes will at least get 50% of the market.
- Aug 2, 2000
- 13,504
- 19
Keep hope alive :rotfl:jaguar said:
Lots of people are faster on 250f's than 250 2 strokes. They're less tiring to ride for those of us who's physical fitness levels aren't fantastic. A 250 2 stroke is no doubt faster in a straight line. After several laps on a hot summer day I start to make little mistakes that have a tendency to turn into bigger mistakes on a 250 2t. The 250f is safer for me if nothing else.
- Aug 2, 2000
- 13,504
- 19
and therein lies the superiority of the 4-stroke._JOE_ said:
2-Strokes 4-ever
~SPONSOR~
Live dangerously. Ride a 2-stroke... ya sissys :p
robwbright
Member
- Apr 8, 2005
- 2,283
- 0
An interesting piece on emissions - not that I have any personal concerns about them:
http://www.snowtechmagazine.com/articles/2002/parrallell.php
The development of direct fuel injection systems (DI) had removed the main drawback of the two-stroke – loss of fresh charge out the exhaust port before compression can begin. With charge loss stopped by DI, the advantages of the two-stroke stand out. They are;
(1) Low friction as a result of having no valve mechanism
(2) Low pumping loss from nearly equal pressures acting above and below its pistons (pumping loss is considerable in four-strokes operated at part-throttle).
(3) Simplicity - a low parts count (two-stroke cost-per-horsepower was estimated in 1991 as 70% of what an equivalent four-stroke would cost).
(4) Compactness. Low engine height results from having no valve mechanism above the cylinder head.
(5) Naturally low emissions of nitrogen oxides (NOx), the most difficult-to-control of pollutants. This results from the two-stroke’s “natural EGR”. The unavoidable dilution of the fresh charge by exhaust residuals reduces combustion temperature, thereby cutting NOx generation.
(6) A combustion chamber of such simplicity of form that it burns its fuel-air charge approximately twice as fast as an equivalent four-stroke, whose chamber is complicated by the presence of valves.
Two-stroke DI with low-load stratified charge gives a two-stroke engine the same steady, regular idle as a four-stroke. Because it cuts off all loss of fuel out the exhaust port, DI greatly increases fuel economy and cuts exhaust emissions of unburned hydrocarbons and carbon monoxide (CO). The result is a highly efficient and low-emitting engine. At one time, DI technology was regarded as complex and expensive, but the increased complexity of systems required on automotive four-strokes has made this seem routine and practical.
All engines of the future – of whatever type - will carry heavy loads of sensors, actuators, and computing power to make them give the performance we want while preserving air quality and fuel resources.
This bring us to Ski-Doo SDI – a quite different and more economical route to low two-stroke emissions and fuel consumption. SDI stands for Semi-Direct Injection, and it describes a system by which fuel is injected, not into the combustion chamber, but into the fast-moving air streams in the rear transfer ports. Because injection into the transfer streams more than doubles the amount of time available for evaporation of the fuel droplets, specialized fuel injectors like those of Orbital and Ficht are not needed. Direct Injection must wait for the exhaust port to close before injection can begin, but with SDI, keeping fuel from reaching the exhaust is accomplished by the natural scavenging flow pattern of a high-powered two-stroke.
If the engine is carbureted, the negative exhaust wave pulls air and fuel from the intake, and some is lost out the exhaust. This is acceptable in a racing engine, but in emissions-regulated engines it is not. Therefore Yamaha’s four-stroke snowmobile engine, which is at present carbureted, must limit overlap timing to keep emissions low, and must therefore forego this source of extra power. If that extra power is needed in future models, fuel injection must be adopted on this engine, as indeed may be required if emissions regulations tighten further. Four-stroke fuel injection timing can be controlled, just as it is in Ski-Doo’s two-stroke SDI system, so that fuel is injected only into air that cannot reach an open exhaust port.
Seen in this way, two-stroke and four-stroke engines are not as much different as they are similar. They are two different types of air pumps, but both must intake, compress, burn, and exhaust air and fuel, with the most complete combustion and without loss of fuel to the atmosphere. Both must display low losses in friction and pumping, both face the same economic laws governing their manufacture and sale. Both require considerable help from sensors and computers to accomplish their goals.
The two-stroke is light and compact. The four-stroke, while heavier, has an exhaust sound that many prefer to the two-stroke, and a powerband that is flat and easy to use.
Both can meet emissions regulations, and both require computers and sensors to deliver their performance.
http://www.snowtechmagazine.com/articles/2002/parrallell.php
The development of direct fuel injection systems (DI) had removed the main drawback of the two-stroke – loss of fresh charge out the exhaust port before compression can begin. With charge loss stopped by DI, the advantages of the two-stroke stand out. They are;
(1) Low friction as a result of having no valve mechanism
(2) Low pumping loss from nearly equal pressures acting above and below its pistons (pumping loss is considerable in four-strokes operated at part-throttle).
(3) Simplicity - a low parts count (two-stroke cost-per-horsepower was estimated in 1991 as 70% of what an equivalent four-stroke would cost).
(4) Compactness. Low engine height results from having no valve mechanism above the cylinder head.
(5) Naturally low emissions of nitrogen oxides (NOx), the most difficult-to-control of pollutants. This results from the two-stroke’s “natural EGR”. The unavoidable dilution of the fresh charge by exhaust residuals reduces combustion temperature, thereby cutting NOx generation.
(6) A combustion chamber of such simplicity of form that it burns its fuel-air charge approximately twice as fast as an equivalent four-stroke, whose chamber is complicated by the presence of valves.
Two-stroke DI with low-load stratified charge gives a two-stroke engine the same steady, regular idle as a four-stroke. Because it cuts off all loss of fuel out the exhaust port, DI greatly increases fuel economy and cuts exhaust emissions of unburned hydrocarbons and carbon monoxide (CO). The result is a highly efficient and low-emitting engine. At one time, DI technology was regarded as complex and expensive, but the increased complexity of systems required on automotive four-strokes has made this seem routine and practical.
All engines of the future – of whatever type - will carry heavy loads of sensors, actuators, and computing power to make them give the performance we want while preserving air quality and fuel resources.
This bring us to Ski-Doo SDI – a quite different and more economical route to low two-stroke emissions and fuel consumption. SDI stands for Semi-Direct Injection, and it describes a system by which fuel is injected, not into the combustion chamber, but into the fast-moving air streams in the rear transfer ports. Because injection into the transfer streams more than doubles the amount of time available for evaporation of the fuel droplets, specialized fuel injectors like those of Orbital and Ficht are not needed. Direct Injection must wait for the exhaust port to close before injection can begin, but with SDI, keeping fuel from reaching the exhaust is accomplished by the natural scavenging flow pattern of a high-powered two-stroke.
If the engine is carbureted, the negative exhaust wave pulls air and fuel from the intake, and some is lost out the exhaust. This is acceptable in a racing engine, but in emissions-regulated engines it is not. Therefore Yamaha’s four-stroke snowmobile engine, which is at present carbureted, must limit overlap timing to keep emissions low, and must therefore forego this source of extra power. If that extra power is needed in future models, fuel injection must be adopted on this engine, as indeed may be required if emissions regulations tighten further. Four-stroke fuel injection timing can be controlled, just as it is in Ski-Doo’s two-stroke SDI system, so that fuel is injected only into air that cannot reach an open exhaust port.
Seen in this way, two-stroke and four-stroke engines are not as much different as they are similar. They are two different types of air pumps, but both must intake, compress, burn, and exhaust air and fuel, with the most complete combustion and without loss of fuel to the atmosphere. Both must display low losses in friction and pumping, both face the same economic laws governing their manufacture and sale. Both require considerable help from sensors and computers to accomplish their goals.
The two-stroke is light and compact. The four-stroke, while heavier, has an exhaust sound that many prefer to the two-stroke, and a powerband that is flat and easy to use.
Both can meet emissions regulations, and both require computers and sensors to deliver their performance.
And ohhh baby for a 2 stroke MX bike with all the sensors and efi?
2strokesrock
Member
- Oct 7, 2008
- 204
- 0
Here is a link to an article about the new KTM fuel injected two stroke :) can't wait to see it!
http//twostrokemotocross.com/2009/02/coming-soon-ktm-fuel-injected-two-stroke/
I hope the link works.
http//twostrokemotocross.com/2009/02/coming-soon-ktm-fuel-injected-two-stroke/
I hope the link works.
Nope, needs a little more R&D?
Oh boy, I am really curious about Rich's thoughts on this? I know, its a ktm, but! Thanks for fixing that Gary, touche!
The better question is, will KTM even survive? Things aren't looking to good for them as of late.
The mini bike lead scam? Or just the economy? They sure have a good stake in them little bikes. But, if there was one company that used some quality paint?
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