Hi Mark,
Yes I've seen tracks that get warped or twisted way too often. I'm not really sure what causes it. It could be that they take a set when they sit for a long time or maybe one side sees the sun and the other is in the shade and rubber gets effected differently. Finding a straight pair and then get them to be the same length can be a challenge sometimes.
You might want to try something like putting a 2x8 on it and put something heavy on it. Then try and pull the tracks straight while under pressure to hold them in place once you get them moved. Then wait a few days and see if they improve. Just a thought. Never tried it, but if you can't match up a pair, it may avoid you buying another set.
I see your 500 chassis is pretty rusted and may have some modifications made to it. If that chassis is questionable, I have some 500 chassis that are in pretty good shape. You can email me or call me if you want to discuss further.
Good start my friend. Another 500 brought back from the grave yard. Good Job!
Bruce
Too many Diablos and parts to count.
Yamaha 600 SX