The reason why 2 stroke dirt bikes are carburetor is money, but not for the cost of the EFI. the manufacturers make more money selling us parts for our 4 strokes. Years ago a friend of mine wanted to import Husaberg into Canada. While at the Husaberg factory in Sweden he asked the same question. They make more money selling parts for 4 strokes. IMO if manufacturers did R&D on 2 strokes again we would have better bikes that cost us less money to maintain and repair. A couple of us have been playing with the idea of using KTMs ignition and EFI management system on a CR 500. Before someone says it can't be done because it only sparks on every second stroke, KTMs use a wasted spark system. Which means it sparks on every rotation. Set up a crank sensor(missing tooth/reluctor wheel) maybe a Dobeck controller and start your own R&D. It's too bad I'm just a poor electrician and don't have the time. But if I win the lottery I'm doing it. Some guys in New Zealand put a CR 500 into a YZF 450 frame and fuel injected it. You can Google it. I tried to track them down, but couldn't make contact.