A 2 stroke CAN be made to no longer be Fully dependent, or have any dependency on Any inlet ports, other than the injector itself. That it Can be done, sure as hell doesn't mean it will be done.
DFI can be made to deliver the Entire fuel / air charge to the combustion chamber. But, it's not very practical - a very uncalculated (just to cover myself with regards to pedants) assumption is that the 'charging system' would be very large / bulky /heavy/power draining etc. etc. With no charge generating parts, the carriage of sufficient air / oxygen charge storage would be rather 'difficult' to deal with.........
.
So. it is a very doubtful thing that it would ever appear on a motorcycle, of any type.
For 2ts to remain available for Any applications, in the future, more than just a carb is going to be needed. AST, trapping valves, AR, and Many other techs are out there to enable continued use of carbs. EFI, just an electronic carb, used with the previous sentences techs, is a possibility, to meet coming regulations. I recently had a very serendipitous encounter, and a subsequently long discussion, with a high level person from Victa Australia , and their commitment (and, now, Briggs and Stratton [sp?], their 'owners' ) to 2ts for future use over 4ts was very encouraging. DFI, is just another way to deliver fuel / air charge, to deliver improvements - more than just the environmental and fuel economy that is so largely at the forefront for it's coming use. But environmental issues and economy are what is focused on with 2ts (and 4ts), by legislators. Unfortunately, the very real advantages 2ts already have in terms of production environmental costs, and 'whole of life' environmental costs, has been swept under the carpet
The posting of the Athena video (and the patent numbers) shows that DFI, as most tend to know it (coming in from the Cylinder head), is far from the only solution. When you see companies such as Athena doing this, and, hopefully, having it applied, you know there are a lot more (in terms of numbers)viable solutions than just variations on Orbitals Stratified charge DFI.
Short stroke / long stroke - both have been around for along time. Both configurations (and the mid ground between each extreme), offer advantages. And disadvantages.
4ts went to short stroke for high power applications long, long ago. Check 4t road racers/ multis from the sixties. Your basic XR250 was a very over square engine compared to the vast majority of 2ts. The over-square dimensions have just got a bit more extreme. What's the general F1 V8 dimension - 90/92(?) x 39.?mm, now? Ironically the KTM 350 has lesser over-square dimensions than the 'Berg 390 / KTM 400. The previous 'split case 'Berg 450 was a higher bore stroke ratio again. Close to, or at 1.8 to 1, I think? Yet it wasn't set up to be much of a 'screamer'.
For dirt use, we are talking about limited traction. So, we don't use engines highest levels of tune - not even if they are true tiddlers - we need tractability and a reasonably wide spread of power. Electronics, further development will help with usability issues, when going for higher and higher outputs - but, as ever, it means more complication, and higher costs. So goes it.
There are people here getting Long Rod set ups, confused with long stroke set ups.
I'd be happy to just play with a simple Keihin carb, but, I'll deal with Whatever is required to keep 2ts available to me. And I'll be trusting (naive?) enough to expect that it will deliver real improvements, just as the majority of new tech has done during the development of ICE engines.
DFI kits have been used in Asia, to clean up the emissions from millions of little 2ts engines, that are in use there.
2tInstitute:
You've seemed to be a bit negative with regards to DFI, for quite some time, here. These are questions, not attacks, on you:
Would I be correct in thinking it might come from a perspective of it not being the Only solution available to apply to 2ts?
I can see that as being a very valid point, hence my always citing other techs available for use in 2ts. I share that line of thought to a certain extent.
I do, however, think DFI may become the 'norm', as, like so much in engineering, the one solution is inevitably focused on by manufacturers, if it has proved to be viable, and cost effective - if only by it's sheer weight of numbers. A simple example, being the almost exclusive use of the Keihin FCR carbs (a lower tech example, certainly, but a hell of a carb) with 4t dirt bikes, up till recently.
Bringing us , the long way, back to current 4t ascendancy over 2ts
