Can I learn in a 600cc motorcycle?

600 cc cruiser no problem. 600 cc sport bike not a good choice. 600 cc standard not terrible.

You can. People have, But, it's seriously not recommended.

If you cannot stand the thought of riding the Ninja 250 or 300, then consider the Ninja 500 or the Ninja 650.

Yes, I know I threw the 650 in there and that's bigger than the 600, but that's not the case. The 650 is actually a good starter bike, especially for bigger or taller people. It has half the HP of the 600 and is much easier to ride.

600cc sport bikes are pretty much race bikes with lights. You didn't learn to ride a bicycle on a $12,000 carbon fiber 5 pound race bike, you started with a tricycle. You learned how to crawl before learning how to walk. So take the hint and do the motorcycle thing the same way. Get the smaller bike, then move on after a season or two.

I'm in the process of moving from a 250 to 600cc. I've ridden for a season in rain, wind, cold, hot, highway, twisties, short rides, long rides, high traffic, low traffic..as much as I could possibly ride (i'd keep the 250 too but I don't have place for it at my apartment), and honestly I can easily say that I'm glad I started on a 250. There have been instances where I've recovered from near highsides..if I had a 600cc and the same thing happened, the sensitive throttle would probably have caused me to go flying. It's a lot easier to practice and develop skills on a bike which won't throw you off as easily lol

Type, model, year ?

Some 600 ccs are big heavy and slow some 600ccs are high revving high performance track focused bikes.

It's not really about the actual cc it's more about the torque, bhp, weight etc.

Some 300-400 ccs will be far faster than some older 600ccs.

I started off on a 500cc motorcycle. The only thing that you will experience with a 600cc motorcycle is how much harder it is to turn on them since they are much bigger and how sensitive the accelerator can be. Other than that I think for a beginner a 600cc motorcycle should be the limit to practice on.

Yes, but trust me on this: you are not a safe rider.

Thee is no such thing as an unloaded gun, and there is no such thing as a safe motorcyclist. Did you ask your instructor for any advice on what bike to start on? My advice is to go with his advice.

Well, I learned on a 650

You should be fine as long as you keep the revs low and do not try to be stupid in the corners