Why was Suzuki Motorbike Katana 750/650 discontinued?

Because the katana was slow, ugly, heavy, and handled poorly. Katanas are as ugly as busas, but at least the busa is fast and aerodynamic!

Take a look at the SV650 and SV1000 if you want a manageable learners bike which is cheaper than a gsxr

I cant answer that one but I presume that if you are in the US if you are calling it a Katana. I have a 99 GSXF750 that I bought new and other riders still ask me if it is and think it is a great bike. The engine still pulls hard when it has run off the speedo at 260kph and it handles like its on rails. It may be heavy especially on the front but that just means that the front stays down to give better stability and put the power to the back wheel where it belongs. It is by no way the number one performer in any catagory but if you get into a situation where you may need to change you pants afterwards the bike will forgive you and get you out of it. If you want one have a look around for a second hand one. Make sure it is clean, scratch free and has been serviced as per the book. Like any bike if you do not look after it it will turn into a dog.

Because they were lousy bikes. Katana aka Lead Sled, Can-a-Tuna. They're heavy, slow, and sloppy.

the katana is a gsxr not discontinued retooled and thusly renamed

because it was a long outdated motorcycle with quickly declining sales against more modern competition. believe me it was time for it to go.

they weren't saleing the style got buring.