I just blew up my 240 and am thinking about a yz250 or 490. Just for drag racing so I am not worrried about the vibration. I already have the extended swingarm 8" so it will handle the power. Im just looking someone who has done this.

 

If you haven't caught my sig, I am in the process of putting a '84 air cooled YZ490 in my blaster. The 490 is quite a bit larger than a blaster engine. The air cooled YZ250 uses the same frame as the 490 so it is almost the same size. They will fit with custom brackets, though. They hardest part is trying to find a pipe for this. Eight inch swingarm will help, but just remember that the 490 turns more horse and torque than a stock banshee.

 

My friend has a old 79 yz 250 motor in his blaster it runs way better than the blaster motor but vibrates pretty bad.