i was just wondering if any of you know or have ever tried putting a ktm 450cc 4-stroke engine in the stock z400 frame. i know i may have to do some custom frame work to make the engine fit but does anyone know how much work would have to be done?

 

If you have to ask, it's probably more than you would care to do.

People have put just about every type of engine in every type of frame. Like you said, you would have to do some fab, but with enough work you can make anything fit.

With that said, why go to the trouble to do that and put it into a frame that has a higher stance than most when you can put it into say a 250R frame and have a lower center of gravity from the get go.

It's a sound idea, just not ideal.