All 2st 2012 2t Rumours

Mercury licensed Orbital's technology in their Obtimax outboards, I've had one of them for 10 years. It's a good running and very fuel efficient engine. The huge downside is that it's a very complex motor and one little hiccup will leave you stranded. The equipment to work on it is very expensive and you need an eletronics engineer to troubleshoot it when it breaks.

If BMW builds a new DI 2T it will take a couple years to work the bugs out.

I say just put Keihins on them and leave well enough alone.

That's one way to look at it, but what if the EPA puts restrictions on the off road motorcycles? Then you be left with either, older equipment that is exempt, or four stroke engines. Even if all two stroke engines went to DFI and you did not like the concept, how hard would really be to install a carb. I think it will be good for the industry, but the price point needs to be atleast $2k less the four stroke bikes.

Yep, after looking and reading about all this, I'm thinking the complexity is gonna be a down side on this ... Having a 2t break in the woods and U have to tow it out will be bad ... Everyone may not be ready for that scenario ... I was thinking just spray some juice in the cylinder but it ain't that simple ... And the fuel pump is an absolute essential part to DI?

The 2t pipes were a pain for me as I always crashed and bent mine but they were an easy way to entirely change the engine response ... I think could do without one though if the DI picked up the entire engine performance ....

I wouldn't count bmw out too quickly .... U never really know what is going on inside these companies .... Most can have things on the drawing boards yrs in advance of any real PUB ... & they have a long history of making different \ new technology happen ...

You guys are having to much fun!! KTM bashing, I LOVE IT Gassers I like and cut a break. Direct injection Iv'e felt the las couple of years that it will come. Someday, mostly I think because of epa stuff.

I'm just curious - why do some of you hate KTM so much ???

I agree with Kelly's first paragraph. I disagree with Kelly's last paragraph. IMHO, the artistic elegance of the two stroke expansion chamber should never be changed. To me the focal point of any dirt bikes is the pipe. You know at a quick glance if it's a two or four stroke.

Four stroke pipes look like the 1/2 pipe and toy muffler that was on my 3HP Briggs go cart back in the day. I really love the expansion chambers of the mid-70-80's works mx bikes. Would mention a few brands but don't want to advertise.

WR Bob

Walter Kaaden; the father of the expansion chamber, is turning in his grave at such talk!

DI sounds sexy and may be the wave of the future for 2 strokes. I hope husky's right there at the forefront if that's the case.

Whatever happens, it will be an interesting future for 2 strokes and dirt bikes, in general. I'm a 2-stroke guy, although I'll admit the strong points of a thumper. There are definitely strengths and weaknesses to each design. And it's not my intent here to debate them. But when the modern awesome thumpers came out, they raised the price, and they... well... let's say "changed" the maintenance issues of owning a dirt bike.

One thing I like about my CURRENT smokers compared with CURRENT thumpers is the lower initial cost, the lighter weight, the (IMO) easier more straightforward maintenance. Smokers just better suit what I like to do on my dirt bikes. Sure, you could list the advantage of a thumper, too. But that's sort of my point: IF the DI comes with the LOSS of light weight/lower cost/easier maintenance...

Like it or not ... 2t need a kick and this DI stuff is the best thing on the horizon for their existence ....

Husky hopefully can get back into a leading role here with a push here quickly in the very near future ....

I hate Ktm, always have and vill do it forever.
I dont know why?

yes hope husky will move forward in development with the 2t i think thay have fallen behind in the 2t market even a elec start would be progress yes i can hear you all saying what about the weight if other manufacturers can do it and keep weight down why cant husky and then fi that would see them as the dominant leader in the 2t dirt bike industry

Not sure I agree with this. The purpose of an expansion chamber is to scavenge exhaust and to increase the overall charge. How else would you do these on a two-cycle engine, even if it did have DI EFI? Super-charging is one historical way, but I’d be inclined to feel that would be impractical on a dirt bike.

I've said it before, and I'll say it again. I'll buy the first DI 2 stroke enduro bike available. I hope it's a Husky!

In terms of weight, I don't think we're looking at a drastic increase. Yes, the fuel pump is added weight, as well as more electronics (sensors, robust computer). I guess other sources of weight might depend on the exact approach to injection, as well as oiling concerns. An oil tank might be needed to supply oil to the bottom end, but it likely wouldn't need to be very big. The air injection of an Orbital design is simply a little cam attached to the crank that runs a little air pump each time it comes around, so that's not too much more weight. It all adds up, of course, but I bet it'll still be significantly less than a 4-stroke of comparable output. Plus, if you believe the internets, the amount and quality of power will allow smaller engine displacements than even comparable 2-strokes. Some weight savings there.

In any event, I'm looking forward to trying one.

What you're scavenging in a traditional 2-stroke is the fuel and air that escaped into the exhaust during the overlap of the intake and exhaust ports. I guess if the port timing is optimized to minimize the amount of air lost out the exhaust port, then you wouldn't need to scavenge any, therefore no expansion chamber. But you might be able to get a nice supercharging effect at certain rpm if you kept that port overlap and expansion chamber. I could see it working either way.

Rasputin,

The whole key to this is the direct injection. This injects the fuel charge directly into the combustion chamber after the exhaust port is closed. Completely different type fuel charge than a carb or port injection. This is the only way to insure that the fuel charge does not escape out the exhaust port and contaminate the exhaust and lead to inefficiencies when operating outside the timed back pressure range of the expansion chamber. Direct injection allows the computer to completely adjust the charge and timing to optimize power and torque at all rpms. The expansion chamber would only be used as an atmospheric air charging of the combustion chamber rather than letting the transfer of the air escape out the exhaust port during the overlap discussed above. With direct injection there are several ways to overcome this but I think there is a point when excessive complexity might be a detriment in the dirt bike environment. Just a basic Direct injection model with computer controlled fuel and spark delivery added to the expansion chamber cylinder stuffing will still lead to a 4T like power delivery but more everywhere cc to cc. I still think that the biggest hurdle to this has always been the consistent lubrication of all the moving parts without a crankcase full of oil. I think modern micro pumping with computer controls have solved a lot of this. I think it will be really cool to see a two stroke rod with an oil passage cast into it.

I am obviously no expert and can't wait for the experts to produce something we can all appreciate.

Walt

Rasputin is right, brief, but right.

In a current 2T the expansion chamber helps draw out the exhaust, then over draw new mixture and pushes it back in to increase the charge.

In a DI 2T, the only difference will be that the gas is not added until the ports are sealed. Given a piston port and reed valve design the expansion chamber will be very bit as important.

Some DI 2Ts use a poppet valve instead of exhaust ports. In that case, they usually use some way to provide greater than atmospheric pressure at the intake. Some diesel engines are designed this way. Others have even added exhaust extraction turbines where a decent length of exhaust pipe is not possible. For a big, low revving engines (automotive, trucking, shipping), this is far better than designing in multiple gigantic expansion chambers. It also provides for more constant torque over the entire rpm range. We all know expansion chambers do not do this.

Story time - I traveled on a ship about 30 years ago that had a 4 cylinder, direct injection 2T engine than employed exhaust poppets. Bore and stroke of each cylinder was 1 meter, and maximum rpm was 180. While the intake compressor was relatively compact, imagine the size of expansion chambers they would have needed!!!

In any case, for MC applications where the engines rev high and have small displacement, I expect any DI application will continue to use expansion chambers for weight, cost and complexity considerations.

I’ll shut up now.

Jake just informed me that Rasputin is involved in the 2T developement at Husky. As I told him it is a good thing that the cow sh!t here in Montana is such a fine variety as I often get to taste it off the bottom of my foot.

Walt

This is some good reading and funny to thanks to Walt. When and if it hits the market I'll be at the tail end of the line to test it out.