Katana Owners Club U.K.

Hi, is it possible to fix a new engine (from gixer 750 for example or some other Suzuki 750-1000 cc) on Kat 400 frame with minor changes?

Well....the basic answer is yes as it's been done. We have a guy with a gixxer1100 engined 400. Having said that it's a lot of work. However,I've got a GSX600 engine to go in a 400 and from my basic measurements it'll go in (just).
As I'm sure you're aware the 400 engine is tiny and there's not a lot of room in there. I personally think an oil-cooled gixxer750 will probably go in, it's just that I got the 600 real cheap.
I know your prices are pretty steep over there but you could fit a 600 with a big-bore kit (a bandit 600 can go to 840cc) but financially that would be expensive.

You also mentioned 1000 cc engines. These are quite small, so maybe they fit better than the oil cooled lumps. But I don't know of anybody who did that job yet.

the 4/11 (its the orange one)

Harry had to cut, widen and weld extra metal to modify his frame to fit the oil boiler motor!

So not a straight forward job...........