It's been done on a bike, didnt work very well.

Bomb seems to be the leader in keeping 2 stroke recreational vehicles on the market, and sometimes seems like the only one as more and more companies switch to four stroke sleds and PWC's. I expect that to continue long past the 2006 model year and eventually bring some other companies along with them to the 2 stroke market.

 

The rotary bike didnt work because it used a secondary plug only and not a primary and secondary like the mazda. With a little more effort on the RE3 ? engine it could have been a screamer. Mazda does 9000 rpm smooth as glass with little effort. With some hardened side gears and eyebrow porting rpm could easily go to 10,000 plus with plenty of torque. The mazda is only 1300cc afterall (13b) and does a respectable job of hauling the rx8 around.

Steve Lubecki

 

LMAO!!!!! Zbart1, you have brought nothing to this thread. Your post and comments make you sound very inmature. If you can dispute the facts I have posted then fine. But do so with real information and not personal attacts. And I might add that I am not here to impress YOU!
Now having said that, if I "disappointed you so greatly" with posting a few facts. Then WOW, you have got a whole life time of "disappointments" ahead of you young man! You see the World is full of information and facts that you are obviously unable to understand or execpt.
I am not plugging BRP. I don't even own any myself. I was commenting on the technology. Not there products. Now Zbart1, seeing that you can not read. Or understand what you read. Then yes, perhaps you should be done with this thread.
Hope I haven't " disappointed " you to much with a few more FACTS!!!!!!!


p.s. oh just one more thing, I was looking at some of your 83 or so post.The two posts that say "HOW DO YOU GET OCTANE RATINGS OVER 100?" are cut and pasted... LOL!!!!! Looks like you are an expert when it comes to the cut and paste thing huh???? POSER!!!!!!!!!!

 

LOL!!! BUT and I say but..... But what???? I didn't know YOU made up the rules here DaD!!!!!!
What line???? Your line???????
Are we dancing now???? Is this called line dancing?????

 

I would like to get this thread back on track concerning by talking about the various two stroke technology.

First there is the fuel management. It seems to me that this comes in four flavors, carbs, fuel injection, semi-direct fuel injection and direct injection.

The carbs we are all familiar with. The big change with many sled engines is that there is now on-board computers to support spark control with these engines. Along with the computer comes digital ignition. The digital ignition allows the engine to change the engine spark timing to create reverse by running the engine backwards. Only Ski-doo and Polaris have the electronic reverse, but all the sled manufacturers have computers on the new sleds. The problem with carbs is that raw fuel often times goes out the exhaust as the transfer ports and exhaust ports openings overlap. Currently all sled manufacturers, some of the outboard motor monufactuers, ATVs and diret bikes have carbed two strokes.

Normal fuel injection as we think of has fuel injection in the intake manifold, before the reeds. This type of fuel injection is basically a replacement for the carb. Artic Cat has had this type of fuel injection for years and their F7 is legendary. This type of fuel injection has the same problems as the carbed engines; raw fuel in the exhaust.

Semi-direct injection moves the injectors from the intake manifold to the transfer ports of the engine. The idea of semi-direct injection is the injector squirts the fuel through the transfer ports into the combustion chamber just before the transfer port closes. This assures that no raw fuel goes out the exhaust port unlike carb two strokes. There are two injectors, one points into the combustion chamber through the transfer port, the other is just below it. The first injector is used during idle and part throttle to carfully control fuel flow into the combustion chamber. The second injector opens at high throttle settings to supply additional fuel. Both Ski-doo and Polaris use semi-direct injection on some of their two strokes.

Direct injection moves the fuel injectors directly to the combustion chamber. These solution injects fuel directly into the combustion chamber after the exhaust port closes. So there is no raw fuel going out the exhaust. Direct injection requires a high pressure air pump running at 250 PSI to force the fuel into the combustion chamber. This high pressure also atomizes the air to support complete combustion. E-Tec adds stratified charge which is a concentrated area of fuel/air to support low fuel comsumption at idle and low throttle conditions. The problem with direct injection is that it requires this high pressure pump with its own pistons and valves. This adds weight and is just something else to go wrong. Direct injection is used on outboard motors and Seadoo has used it for a number of years in Jetskis.

My first choice in two strokes is carb; for simplicity and cost. However, if the greenies force me into a cleaner motor, my personal opinion is that semi-direct injection is the way to go when you are concerned with reliability, cost and weight. It has the advantages of direct injection, but the simplicity of fuel injection. It may not be quite as clean or efficient as E-Tec at idle, but then it is where it needs to be for emissions.

Bryce

 

Well, I think we all can agree that their are certain applications that it would be very hard to replace a 2 stroke with a 4 stroke examples being ( weed trimmers, chain saws, leaf blowers ).
You said it your self Bryce and I agree with you. "Simplicity and cost." These are just two of the reasons why i think there will be more companies willing to spend money on R&D and continue to develop new and cleaner burning 2 stroke engines.

Now the marine industry is just one example of where some people may not want the extra weight, maintenance, and cost of a 4 stroke engine for there boat. Also cost of material, labor for assembly is much higher for the manufacture. Witch must be passed on to the customer. And even after the initial cost, the maintenance for the 4 stroke cost more and must be done more often (on the outboard engine).

Also, the consumer wants (low cost, low maintenance, and they want reliability). And so does the manufacture. Now most of the 2 stroke engines we see today use technology that is decades old.
Look at the Banshee engine. It's 60's technology from one of Yamaha's old 2 stroke street bikes. They have been using this design for almost 40 years! Now because of changing laws. The manufactures are being forced to produce cleaner engines. I do not expect the new generation of 2 strokes to be as simple or as cheap to produce as the o'l Banshee engine was.
However the cost of the new 2 stroke technology will come down in time. And I do believe it will cost less to produce a new generation 2 stroke when compared with the cost of producing a similar model 4 stroke. But lets set the cost issue aside. There are still advantages that a 2 stroke will always have over a 4 stroke. That being better power to weight ratio, less moving parts and rotating mass, and 2 strokes can be run in all positions.

I guess after reading up on some of the new 2 stroke technology, I just kind of see the glass as half full instead of half empty....[img]i/expressions/face-icon-small-smile.gif[/img]

 

On the SDI and DI, how do the crank bearings ever get lubrication if all the fuel (and oil) is only getting shot into the top end?




I think there was an Austrailian company called Orbital that was building a 2 stroke for automotive purposes. It had regular 10w-30 in the crank to handle lubrication. Thus, the emissions were about the same as a 4 stroke because NO oil was being burnt in the combustion chamber since it lubricated like a 4 stroke. Obviously it used some form of direct injection too.

 

2 stroke is the champ' choice,don't forget jean sebastien ROY from
the canadian motorcoss series,that guy is the ultimate winner in
the mx1 pro moto for severals years now and run A CR 250 honda 2 stroke.

 

These engines use oil injection. Different manufacturers inject the oil at different places, but the oil will be injected directly into the crankcase or it will be injected into the intake manifold. Carbed two strokes inject oil in the same way. Now what is different about DI and SDI engines is that you cannot premix the oil with the gasoline. Otherwise the lower end does not get lubed.

BTW.. emissions come not just from oil, but also from the combustion process of the fuel. A significant source of emissions with carbed or fuel injected two strokes is unburned hydrocarbons in the exhaust.

Bryce

 

how 'bout some testimonials. 4 strokes generally last longer, well, let's hear from some 2 stroke owners with odometer readings and see how true this is. what are you 2 strokers getting out of your engines before a rebuild? if you take care or your machine, why can't a 2 stroke last as long as a 4 stroke?