Im thing about putting a R motor in my 300ex I have 400ex A-arms shocks off a 250r a 350x swingarm a dura blue axle with all that I have the width and length for the massive power increases but do i need to do more and buying a 400ex and putting the R motor is out of the question is their a kit or and thing of that nature that can help me with this conversion I know that I can make the motor mount up good but where wound i get the pipes and silencer of the R motor that will fit on my 300ex any words of wisdom would be grate thanks

 

What is your reason for wanting to put a 250r motor in your 300ex frame. If you want some handling I keep the motor in the 250r frame so I would have the great power and the great handling of the 250r. Just my $.02.

 

True, just buy a 250r.

Do the math, an engine in good shape is going to cost you $800 - $1000. So you need $1000 at least, anyway.

Sell your 300ex for $2000, now take the $1000 your where going to spend on the engine and you have $3000.

$3000 will buy you a decent 250r and you don't hve to worry about the pipes not fitting, the kick start clearing the frame or finding a place to put the radiator. You would also have to rig the motor mounts and gusset the frame to handle the extra HP even though the 300ex frame is pretty strong.

There is like 5 250rs in that price range right now on ebay.