Foo - is it true?

is it true that most dirtbike companys are goeing to stop the production of two strokes?

hmmm... this is a bicycle forum, but from what I can tell yes, due to EPA regulations. They've made PWC (personal watercraft or jetskis) go mostly 4 stroke, and the stand ups which are still 2 strokes are not allowed to be sold in some states. I imagine it is only a matter or time till there are no more 2 stroke dirt bikes.

Yep. Thank the EPA

Would 2 cycle engines meet the EPA regs if they stopped mixing oil woth the fuel and lubricated them like a 4 cycle engine? I also undestand they will stop making 2 cycle outboard engines.

Joe

My jet ski is a relic then!

I think someone's got the wrong forum.

I think someone's got the wrong forum.


Not really. This section is called "Foo" (Off-Topic chit chat with no general subject.) A valid post as Bridge vs Implant.

Would 2 cycle engines meet the EPA regs if they stopped mixing oil woth the fuel and lubricated them like a 4 cycle engine? I also undestand they will stop making 2 cycle outboard engines.

Joe

a 4 stroke usually has a seperate crankcase for the oil, where the 2 stroke uses the crankcase as a pressurization chamber to force the fuel/air/oil mixuture into the cylinder.

2 strokes are lighter and can work in any orientation. The motor is lubed by the fuel air mixture being pulled into the crankcase. If you turned a 4 cycle upside down you would probably stave the oil pickups and run the bearings dry.

You could theoretically run a seperate oil system, and a seperate fuel system, but this takes away from the reason manufactures used 2 stoke technology to begin with. low cost, and lightweight.

Even if you kept the oil seperate from the fuel/air mixture, You will always get some fresh unburned fuel mixture running across the piston head and out of the exhaust port into the air or water. As you only have one stroke to both clear the cumbustion chamber and fill it up again.

as far as i know in ca they wont even issue all season ohv permits anymore to people with 2 strokes ... i could be wrong though.

what are they gonna do about weed eater engines?

Weed eaters are safe for a little while at least. Probably for a long while since they can't seriously contribute much to the overall pollution. I know somebody, I think Ryobi, does or did for a while make a 4-stroke with some kind of unique pressurized oil system that would theoretically work in any orientation. It's been a while since I saw anything about it.

There's a lot of changes going on like this. My school is right next to Freightliner, the truck company. A person I know who works there says they're being required to make some very drastic changes for their 2007 lineup. I guess the engines will actually be re-ingesting some of their own exhaust to help burn up some of the partially combusted fuel that normally gets expelled. One of my profs, who worked on the research that suggested this solution pointed out that it cost a lot in R&D and will cost a lot more in manufacturing to improve the engines, but very little is done to clean the fuel , which is the source of much of the bad emissions. Interesting how lobbying works, isn't it? And before someone says it, no it's not just a Bush thing, it's been this way quite a few years.

I guess the engines will actually be re-ingesting some of their own exhaust to help burn up some of the partially combusted fuel that normally gets expelled. One of my profs, who worked on the research that suggested this solution pointed out that it cost a lot in R&D and will cost a lot more in manufacturing to improve the engines, but very little is done to clean the fuel , which is the source of much of the bad emissions. Interesting how lobbying works, isn't it? And before someone says it, no it's not just a Bush thing, it's been this way quite a few years.

That's been going on for YEARS. Every single car I've worked on (and it's been quite a few) has an EGR system that circulates some of the exhaust back into the intake tract for lower tailpipe emissions. However, I think you're talking about diesel engines which are relatively clean-burning engines, well as long as they're in tune. Diesels have a reputation as mass polluters due to the plumes of smoke that come out of the tailpipe, but for the most part, that plume is simply soot/carbon from an over-rich engine condition.

as far as i know in ca they wont even issue all season ohv permits anymore to people with 2 strokes ... i could be wrong though

The will if it is pre-1996. But again they may have change the law one more time. Atleast this was the case last year. It's been known for a while, that is why Yamaha came out with YZF a while ago and now the others are doing the same.

a 4 stroke usually has a seperate crankcase for the oil, where the 2 stroke uses the crankcase as a pressurization chamber to force the fuel/air/oil mixuture into the cylinder.

2 strokes are lighter and can work in any orientation. The motor is lubed by the fuel air mixture being pulled into the crankcase. If you turned a 4 cycle upside down you would probably stave the oil pickups and run the bearings dry.

You could theoretically run a seperate oil system, and a seperate fuel system, but this takes away from the reason manufactures used 2 stoke technology to begin with. low cost, and lightweight.

Even if you kept the oil seperate from the fuel/air mixture, You will always get some fresh unburned fuel mixture running across the piston head and out of the exhaust port into the air or water. As you only have one stroke to both clear the cumbustion chamber and fill it up again.

Stihl has a new technology that is mostly four stroke but uses an oil mix. It is supposed to run much cleaner. Read about it here. (http://www.stihlusa.com/whatsnew/news_fourmix.html)

Stihl has a new technology that is mostly four stroke but uses an oil mix. It is supposed to run much cleaner. Read about it here. (http://www.stihlusa.com/whatsnew/news_fourmix.html)


Cool,

Its a 4 stroke with a split intake manifold, the majoirty of the fuel/air/oil mixture goes to the cylinder, a small part gets pulled into the crankcase for lubrication.

It meets the EPA emissions guides due to the exhast valve.


I found this link.

http://www.popsci.com/popsci/bown/2003/article/0,18881,537079,00.html

The oil in the fuel is not the big emmisions problem with a two-stroke it is the fixed "valving" determinned by the ports position that allows the transfers and exhaust to be open at the same time so some unburned fuel escapes the system.

The trick is to build a forced induction two stroke with intake ports and exhaust valves and fuel injection (Like a Detroit Diesel) Yamaha and some others have developed motors alopng these lines. They should be more powerful; and efficent than a four stroke because they make power every piston stroke down rather than coasting through an exhaust stroke.

RedMax and Honda(and probably several others) make four stroke power equipment (string trimmer) engines. They are exspensive to make, because they have a lot more parts. It haven't been in that field for a long time but I seem to remember the RedMax using a closed crankcase with oil. This is tough to do as well because the crankcase needs to be vented so the pressure created by the downstroke of the piston does not damage the gaskets or cause leaks, this vent also needs to positioned so no matter how the engine is turned the vent will not be covered by oil. Then you also need to be careful about oil behind the piston. The piston slamming into the oil can be hard on the bearings.