Is it possible to fit a 86 Honda 250R motor in a 04 Honda 450R frame

[herbie57_57]

its probably possible with some major modifications but you're going to lose a lot out of the power that you would expect out of the 04. that is a pretty heavy duty transmission on the 04 so the bigger motor really helps.

[HondaRider01]

Is it possible to fit a 86 Honda 250R motor in a 04 Honda 450R frame