http://twostrokemotocross.com/2009/09/the-2010-yamaha-yz-two-stroke-line-up/

I'm shocked they still have a full lineup!

Unfortunantly 2 strokes are dirty engines emissions wise.  They produce a lot of unburned hydrocarbons due to the fact that the exhaust port is open while the transfer ports are flowing fresh fuel mix into the cylinder.  It would be hard to build a streetable engine ala supermoto style street machines.

Four strokes engines with a lot of cam overlap are not "clean"  but are better because the exhaust valve does close the exhaust port.

Bimota tried to build a 2 stroke emmisions legal 500 twin a few years ago using direct injecition.  They had a lot of problems getting them to run correctly.

Aprilia built some direct injected 2 stroke scooters but I am not familar how well they worked.

I only own 2 stroke motorcycles and would like to see a cleaned up dirt/street motorcycle.

KTM380EXC,  YamahaYZ250,  Suzuki GT750 and others I no longer own.  MY 2 cents!

GT750's, H1/2 Kaws should have an exemption!  

I think the old bikes are grandfathered in.  I still ride my GT on the street.  I use smokeless injector oil and it does't smoke very much at all.  I use PJ1 Silverfire smokeless.  It's expensive but works well.

Suzuki and Kawasaki had 2nd generation engines on the drawing boards but the emmisions rules couldn't be met with the technology at the time.

supposedly everyone but Honda is trying to build on Aprillas  ground work



I too love 2 strokes and wish for the days of RD350s there is a place local that specializes in making resto parts for 2 stroke yamahas  I need to quit going in there and looking at all his restored bikes  or Ill end up with a 360 again
 

Bimota's problem was that Polini couldn't get the port heights right from cylinder to cylinder and it confused the hell out of the EFI.

Aprilia's scooters work really well.