Looks like Im taking the plunge. 500cc BB 400EX

Im talking with 4ST about machining my 400EX motor to 500cc. From what ive read this kit is quite reliable. Hoping to get this done sooner than later. $$$$$$$
Any thoughts?

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IMO, you would be way better off getting a 450r. That kits gonna cost some pretty good money. And it won't be reliable, atleast not like a stock 450r. I don't see that it would be honestly worth it.

The complete kit plus parts machining and labor is far less than even a wrecked 450. I was planning on buying a kfx700v instead but ididnt have the funds. Im figuring i pay as i go at this point. As far as reliability your probably right but im hoping that 4ST are professional engine builders

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Figure this. Sell your 400ex, and use the money that you would put towards the motor. You should have enough to buy a nice 450R. You will have ATLEAST $1500 into the motor, and you could sell your current bike for seems atleast $1800-2000.

But then i would have just a 450r and not a 500r

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No. Slap a 500ex kit on, it will not beat a 450R IMO

it might

Maybe with a larger carb, good intake, and a good exhaust, and shave 40lbs it might. Chances are slim IMO

See :-)

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Get the 450 instead !! you`ll be happier !!cooling it will be a problem !! the 440kits are known for having cooling problems imagine what a 500cc kit will be like !