is there a way to put a 1977 pe 250 motor out of a dirt bike in to a blaster frame. if there is how do u do it

 

is there a trick to get the sprockest lined up

 

Sure, it can be done. To line up the sprockets you'll need to cradle the motor into the frame(you can balance it on a jack) and use a straight edge. This will show you how the motor mounts will need to be fabbed up. I'd consider a larger motor, if you don't have this one just laying around. The PE motor probably isn't much different than a stock Blaster motor. A DT 400 motor would likely fit, and they can be had for relatively cheap. You'd get to stay Yamaha, and the for an old bike the Dt400's rip.