Is there an blade adaptor for the Sport which can allow use of the hb4 blades?
Yes. The same adapter for the ATX can also be used on the Sport.
The HB4 & HB6 use the same adapter btw.
Yes it can-there is an adapter in the package for the sport. I had used the Sport for nearly a year with the triple blades which worked great. Now my local store just sells the 4's so I bought those and even though they adapt to the sport I have not had a great shave with them. I then bought an ATX figuring the 4's would work well with it- again I am not finding it great. My next move is to order some good old triples for my sport and go back to that. Does anyone else feel the same way?
You can use the triples on the ATX, just make sure the blades face the wheels.