How to Verify that a frame is Straight?

[NacsMXer]

Well I took the plunge buying a new frame off of Ebay. I bought a 2003 400EX frame, but right before it shipped the seller called me up and told me one of the lower rails was tweaked. So he offered me a 2005 400EX frame instead.

He said the 2005 frame is straight. It has some paint defects/minor rust but i'm going to be powdercoating it anyway. All I care about is that the frame is straight.

I'm going to receive the frame tomorrow and i'd like to determine that it is indeed straight before I accept it. What's the best way to do it? Use a level? Plumb bob? Just a tape measure?

Here's some pics of what i'm getting:

http://mail.google.com/mail/?ui=2&ik=be4fc1c112&view=att&th=123f254fd628af3c&attid=0.1&disp=inline&zw
http://mail.google.com/mail/?ui=2&ik=be4fc1c112&view=att&th=123f254fd628af3c&attid=0.2&disp=inline&zw
http://mail.google.com/mail/?ui=2&ik=be4fc1c112&view=att&th=123f254fd628af3c&attid=0.3&disp=inline&zw

[riotact]

I would like to know this too.I just picked up a used 06 frame same condition as yours for $100 and it would be a big waste of time and money if it is tweaked after having it pc'd and putting it back together.

[BSTURDIVANT]

Just sit the frame on the subframe mounts with the bottom facing you. Use a wide tape measure or thin 1/8" piece of metal about 1" wide and hold down the middle of frame top to bottom!
Should be dead center all the way down!

[riotact]

Originally posted by BSTURDIVANT
Just sit the frame on the subframe mounts with the bottom facing you. Use a wide tape measure or thin 1/8" piece of metal about 1" wide and hold down the middle of frame top to bottom!
Should be dead center all the way down!

That seemed to work out perfect. :D