I just bought a 98 srx 700 also, I have heard the tracks were crap , but there is a good chance it is already gone or will need changing anyway.
As for the cranks , they didn't recall them but they did warrenty them and when I bought mine I thought the crank was out , yamaha would of still covered it , I talked to the dealer which it was bought from originally and he varified the crank was done.
There was 2 other problems , the break bleed screw was not tight enough from the factory ( which should of leaked already if there is a problem)
and the ski spindles had a problem with the weld penitration.
I called Yamaha gave my V.I.N. and they were not done so they did it for me .
I think they will stand up for there product if you have any know problems.
I have a friend that had a 98 and he had 10000 km with no problems , mine has been great so far and I have 6000km
I do not think you will be dissapointed
Gerry