The only player still doing anything w/ rotary motors is Mazda at this point.
From what I remember there are a lot of problems associated w/ them the biggest is production tolarances, emisions and fule consuption are also concerns. Mazda spent a fourtune getting them to work the largest hurdal was the seals I know they work great now and are pound for pound cc for cc the most powerful motors but I would guess the stumbling block at this point is money. The current motors are very good, would a rotary outperform them enough to justify the R&D cost?
I have for many years wondered the same as you and I thing you could develope a very light very reliable motor that produces a ton of power but at what cost?
Remember every mfg is out to make $$$$$ and super high R&D cost on a product that might scare people of is a very big gamble.
Lastly without valves rotary motor are very pipe oriented like 2 strokes and they tend to let unburnt gas out so I do not think you could meat emmisions regs and still make a light motor in a quad.

 

Back in the 80s GM started a program to make some 2 stroke cars using DI technology. (DI Direct injection - The same technology that allows a 2 stroke to run better with less emmitions then a 4 stroke). The problem was money. They were redeveloping an engine. If they had turned to a 2 stroke engine maker like rotax and brought them into the project we might be driving 2 stroke cars and trucks and loving them.

I was once at a local drag event for imports. I dont really like imports im mostly a domestic guy myself but there was one honda civic there. The guy thru out the v-tech and put in a merc 2 stroke outboard motor engine. This thing had the ultimate sound and compleatly smoked everything. He spun the tires from start to finish as well.

Torque can come from 2 strokes, it all depends on how the engine is designed. I cant belive that with all the numbers pointing to 2 strokes that not one car company has accually tried to put one in production.

 

Why don't they use two-strokes in cars? Imagine seeing every one leave a stop sign or stop light with a 6 grand holeshot, and feather the clutch not to kill it. You can not make a flat USEABLE powerband from a 2-stroke. Due to the operating principles of a 2-stroke, you have a narrow powerband at one RPM range. Either you have low RPM power which gets you away from the line and falls off at 3000, or topend that comes on hard at 6000. I know it can be adjusted anywhere in between, but face it, you will never have the best of both worlds.

I hear 4-stroke guys on here complaining about having to mix their gas, having to ride behind the smoke, and having to listen to the sound. If the fun loving atver won't deal with these small things to go fast, why would your everydriver want to.

Damion backed up my idea of cost effectiveness. However, if you say no money or time is being spent on 2-stroke power and effiencey, you are wrong. I bet their is more money/time put into the 2002 CR250 engine than in the Z06 vette engine. I'll bet dyno tests of two-stroke powervalves have been made in the last year than dyno pulls of Fords new supercharged Cobra engine. Which by the way is making over 400 horsepower according to the mags (Ford always rate low and they say 395), and it weighes about 500-600 lbs. There is still more available power in this engine.

My understanding is that as of Jan 1, 2006, it will be illegal to sell a new 2-stroke engine in the U.S. I have heard this also includes "closed course competetion" machines such as the KX, CR, YZ series of bikes.

Four strokes last longer because they use more rings? What about bearing in a 2-stroke. Also, I see more piston skirt and ring land wear than I do ring wear in a w-stroke. Four stroke last longer because they are kept oiled more due to oil in the crankcase. It is always on the cylinder wall and on the rings.

The only advantage I have heard for a 2-stroke/rotary is more power. You are sacrificing durability, reliability, effiecency, and emissions. I love 2-strokes. For my riding style, they can't be beat. For my driving style, they will never work. As for the rotary, build one that can pull my 24ft gooseneck with 20,000lbs on it like a 460 will with better than 10 MPG and I will be convinced. Oh yeah, don't raise the price either.



On the same line: Did anyone see the CBS news report a couple of months ago about the gov killing 2-strokes? The report was talking about the oil that was being dropped on the ground from various 2-stroke engines. It then showed an outboard, a jetski, a KX, a blaster, and finally a new John Deere riding mower. You could tell the mower had a Kohler engine. Shows how much the media knows about engines though.

 

I have a couple things to add. They might be scattered, sorry thats just how my head works.

I see that most of you don't like four strokes, why? Is it because of the power out put per cc compared to the other 2?

I think Subaru did have a two stroke car. I can't remember the name or the years.

What about radial valves in a four stroke? It seems like that would help power out put. Or what about Desmo style valves would n't they help out a little?

What ever the out come of the 2-strokes the manufacturers need to be shown that their R&D pays off. Just like the Dales like them or not the have stepped up to the next level. The other Co. need to take a look at how they did it and follow suit.

I thought Bosch had DI 2-strokes, or is it just four strokes?

 

What I meant was R&D money on clean burning 2 strokes in motor cycles. Honda has 2 strokes in their 10 year plan so you will see them for a while but all R&D is set to stop as of 05 buy then the 4 stroke will be at the 216lb AMA weight so the 2 stroke will loose it advantage(this comes from Honda).
Close course bike are not included and it is not a 2 stroke ban it is all bikes will have to produce some obserdly low emisions #'s.

2 stokes cant be made to torque? Ever drive a boat? how about this ever see a train that is a big 2 stroke disel and it make a boat load of torque. Ride a CR500 with a knarly pipe and heavy flywheel weight and I promiss you will know torque. The thing is the 2 strokes you are familiar with are how you describe them.

 

We had an 20ft skeeter with hopped up 200hp merc, from a dead stop (they have no clutch to feather) it could literaly roll you over the seat if you werent hanging on. Awesome sound too. Out of water they sound like a top fuel dragster. The reason they have no bottom end tourque is the pipes for them only work for a specific range, use an exhaust with a continously changing expansion chamber it it will be like one long power band all the way through.

The reason I hate four strokes is that not only do you shove some thing down, then lose a ton of energy by turning it around and making it go the other direction, you do it twice for every one pop of energy. Huge energy waste going on. Rotary engine loses a little power due to the wobble of the rotor to create the compression but is way way way more efficent than a piston. Another option now that CVTs are becoming better and better is turbines. They wouldnt be very good in a car because of stop and go driving (they are very ineffeicent at idle) but they could do wonders for a big rig im guessing. The reason you need a CVT for one is they hate to rev up and down, they like to stay at one spot. So many engine options, i have no idea why we are still using the crappiest one around. Can you think of any engine worse than a four stroke piston engine?

I do wish i was an engineer though, I have some great ideas on how to make a 2 stroke make some massive power and get better gas mileage. Mostly preassure operated valves.

 

Im all for newer 2 strokes. i would rather see them than a 4 stroke. everybody makes the gas mixing a big deal but its really not. They say all that smoke is so bad to ride with, i find the smell pretty good to me especially with race gas in it. People say like the banshee had no low end power off the line and such but how can u say that when u can run it on up in the r's drop the clutch and beat everything off the line. I really hope they dont get rid of all the 2 strokes. If they get rid of them all im gonna have to buy a banshee and stockpile enough parts to rebuild it a couple times. It would be interesting to see a rotary with a turbo in a 250r handling frame,i love the reving u can do with them almost like a 2 stroke. i doubt they ever will but who knows. The big deal with the 4 stroke is u can spend so much money in upgrading it when it doesnt respond that well to alot of things. and u can buy pipes a jet kit and filter and make a 2 stroke run like a bat outa hell. Just hope 2 see them not completely phase out the 2 stoke all together but the sad truth is it prolly is.

well just a thought

Ryan

 

what are radial valves or desmo style valves

one thing i think would help a 4 stroke is an intake valve like a reed valve opened by low pressure in the cylender there would be no cam for the intake meaning less moving parts

and what daimon said about 2 stroke desiels talk about scary
we have one on an irigation pump and that thing it so loud

 

I have a 500+hp 2 stroke diesel about 40 ft from my window, fairly loud and it has a muffler about 6 ft long and pretty big around. The actual engine is about is big as a small car though. My gramps parks his RV here. 7 mpg, if i remember right, which would be bad if it werent friggen huge and have a front end as areodynamic as a brick wall. Oh, and just to throw in a lil more luster to the rotary, im pretty sure i read that the new Renesis engines Red line is 10,000 [img]i/expressions/face-icon-small-smile.gif[/img]

On a side note I have talked myself into a new major. I have always loved rotaries, and 2 strokes and anything diferent. Now that I see other people are too maybe it wouldnt be a bad field to get into [img]i/expressions/face-icon-small-smile.gif[/img] . If you see a new quad company open in about 15 years and they make some wicked qauds with wild exotic engines...... Dont expect ANY four stroke piston powered engine though [img]i/expressions/face-icon-small-tongue.gif[/img]

 

I am not real familar with either valve train but I know a little.

Radial valves are exactly what they sound like. Instead of up and down motion to release and bring in gas it spins, like a rotory engine I think. The good thing about them is you don't have to worry about valves floating and such.

Desmo, actualy desmodronic valve actuation, use a arm under the valve to lift it back up instead of a spring. Ducati motorcycles use this style valve train.