hey guys new to the forum thing, i was wondering if the motor from either a 400ex, or a 450r motor will into my 1987 250x. that me and a friend decided to build basically were wondering if the motor will fit in the frame we know there will need to be some mods for motor mounts and electical any help is much appreciated. thanx

 

I wouldn't get a 450r motor. The motor will cost you $2000. Get a yz400. Its cheep and fast as the 450s. You would need to make up all new motor mounts and radiator mounts. You would need to make a oil tank or run the motor wet sump at lesy ou can get it to fit. It will need a kick start extention made. The rear of the frame may need to be notched for teh intake boot.

I put yz426 motor in my 400ex and all the moding only costed $270. I had a guy that welds for a living do it on the side. Took hime 7 hours. You could have the whole converson dun for less than $1000.


or I will sell you a yz426 motor with hinson basket, tusk clutch, 450 exhaust cam along with a white bros full exhaust and moded carb. Every thing the motor needs i would sell for $2000. has 47hp stock so it should have about 50+ hp

 

I've seen guys put the 400ex motor in a 300ex so it can be done. I put a 350x motor into a '88 250x and it made it a whole different bike, tons of torque. Powroll makes a kit to do this and its actually pretty easy